[FFmpeg-devel,4/6] libavformat/webrtc: add common code for WebRTC streaming

Signed-off-by: Michael Riedl <michael.riedl@nativewaves.com>
---
 libavformat/webrtc.c | 398 +++++++++++++++++++++++++++++++++++++++++++
 libavformat/webrtc.h |  70 ++++++++
 2 files changed, 468 insertions(+)
 create mode 100644 libavformat/webrtc.c
 create mode 100644 libavformat/webrtc.h

On Mon, Nov 6, 2023 at 10:20 AM Michael Riedl
<michael.riedl@nativewaves.com> wrote:
>
> Signed-off-by: Michael Riedl <michael.riedl@nativewaves.com>
> ---
>  libavformat/webrtc.c | 398 +++++++++++++++++++++++++++++++++++++++++++
>  libavformat/webrtc.h |  70 ++++++++
>  2 files changed, 468 insertions(+)
>  create mode 100644 libavformat/webrtc.c
>  create mode 100644 libavformat/webrtc.h
>
> diff --git a/libavformat/webrtc.c b/libavformat/webrtc.c
> new file mode 100644
> index 00000000000..75884eac46f
> --- /dev/null
> +++ b/libavformat/webrtc.c
> @@ -0,0 +1,398 @@
> +/*
> + * WebRTC-HTTP ingestion/egress protocol (WHIP/WHEP) common code
> + *
> + * Copyright (C) 2023 NativeWaves GmbH <contact@nativewaves.com>
> + * This work is supported by FFG project 47168763.
> + *
> + * This file is part of FFmpeg.
> + *
> + * FFmpeg is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU Lesser General Public
> + * License as published by the Free Software Foundation; either
> + * version 2.1 of the License, or (at your option) any later version.
> + *
> + * FFmpeg is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> + * Lesser General Public License for more details.
> + *
> + * You should have received a copy of the GNU Lesser General Public
> + * License along with FFmpeg; if not, write to the Free Software Foundation,
> + * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
> + */
> +
> +#include "libavutil/avstring.h"
> +#include "libavutil/opt.h"
> +#include "libavutil/uuid.h"
> +#include "libavutil/random_seed.h"
> +#include "rtpenc_chain.h"
> +#include "rtsp.h"
> +#include "webrtc.h"
> +
> +static const char* webrtc_get_state_name(const rtcState state)
> +{
> +    switch (state)
> +    {
> +        case RTC_NEW:
> +            return "RTC_NEW";
> +        case RTC_CONNECTING:
> +            return "RTC_CONNECTING";
> +        case RTC_CONNECTED:
> +            return "RTC_CONNECTED";
> +        case RTC_DISCONNECTED:
> +            return "RTC_DISCONNECTED";
> +        case RTC_FAILED:
> +            return "RTC_FAILED";
> +        case RTC_CLOSED:
> +            return "RTC_CLOSED";
> +        default:
> +            return "UNKNOWN";
> +    }
> +}
> +
> +static void webrtc_log(const rtcLogLevel rtcLevel, const char *const message)
> +{
> +    int level = AV_LOG_VERBOSE;
> +    switch (rtcLevel)
> +    {
> +        case RTC_LOG_NONE:
> +            level = AV_LOG_QUIET;
> +            break;
> +        case RTC_LOG_DEBUG:
> +        case RTC_LOG_VERBOSE:
> +            level = AV_LOG_DEBUG;
> +            break;
> +        case RTC_LOG_INFO:
> +            level = AV_LOG_VERBOSE;
> +            break;
> +        case RTC_LOG_WARNING:
> +            level = AV_LOG_WARNING;
> +            break;
> +        case RTC_LOG_ERROR:
> +            level = AV_LOG_ERROR;
> +            break;
> +        case RTC_LOG_FATAL:
> +            level = AV_LOG_FATAL;
> +            break;
> +    }
> +
> +    av_log(NULL, level, "[libdatachannel] %s\n", message);
> +}
> +
> +void webrtc_init_logger(void)
> +{
> +    rtcLogLevel level = RTC_LOG_VERBOSE;
> +    switch (av_log_get_level())
> +    {
> +        case AV_LOG_QUIET:
> +            level = RTC_LOG_NONE;
> +            break;
> +        case AV_LOG_DEBUG:
> +            level = RTC_LOG_DEBUG;
> +            break;
> +        case AV_LOG_VERBOSE:
> +            level = RTC_LOG_VERBOSE;
> +            break;
> +        case AV_LOG_WARNING:
> +            level = RTC_LOG_WARNING;
> +            break;
> +        case AV_LOG_ERROR:
> +            level = RTC_LOG_ERROR;
> +            break;
> +        case AV_LOG_FATAL:
> +            level = RTC_LOG_FATAL;
> +            break;
> +    }
> +
> +    rtcInitLogger(level, webrtc_log);
> +}
> +
> +int webrtc_generate_media_stream_id(char media_stream_id[37])
> +{
> +    int ret;
> +    AVUUID uuid;
> +
> +    ret = av_random_bytes(uuid, sizeof(uuid));
> +    if (ret < 0) {
> +        goto fail;
> +    }
> +    av_uuid_unparse(uuid, media_stream_id);
> +    return 0;
> +
> +fail:
> +    return ret;
> +}
> +
> +int webrtc_create_resource(DataChannelContext*const ctx)
> +{
> +    int ret;
> +    URLContext* h = NULL;
> +    char* headers;
> +    char offer_sdp[SDP_MAX_SIZE] = { 0 };
> +    char response_sdp[SDP_MAX_SIZE] = { 0 };
> +
> +    /* set local description */
> +    if (rtcSetLocalDescription(ctx->peer_connection, "offer") != RTC_ERR_SUCCESS) {
> +        av_log(ctx->avctx, AV_LOG_ERROR, "Failed to set local description\n");
> +        ret = AVERROR_EXTERNAL;
> +        goto fail;
> +    }
> +
> +    /* create offer */
> +    ret = rtcGetLocalDescription(ctx->peer_connection, offer_sdp, sizeof(offer_sdp));
> +    if (ret < 0) {
> +        av_log(ctx->avctx, AV_LOG_ERROR, "Failed to get local description\n");
> +        ret = AVERROR_EXTERNAL;
> +        goto fail;
> +    }
> +    av_log(ctx->avctx, AV_LOG_VERBOSE, "offer_sdp: %s\n", offer_sdp);
> +
> +    /* alloc the http context */
> +    if ((ret = ffurl_alloc(&h, ctx->avctx->url, AVIO_FLAG_READ_WRITE, NULL)) < 0) {
> +        av_log(ctx->avctx, AV_LOG_ERROR, "ffurl_alloc failed\n");
> +        goto fail;
> +    }
> +
> +    /* set options */
> +    headers = av_asprintf("Content-type: application/sdp\r\n");
> +    if (ctx->bearer_token) {
> +        headers = av_asprintf("%sAuthorization: Bearer %s\r\n", headers, ctx->bearer_token);

Should check that "headers" is non-NULL (i.e. that we're not out of memory)

> +    }
> +    av_log(ctx->avctx, AV_LOG_VERBOSE, "headers: %s\n", headers);
> +    av_opt_set(h->priv_data, "headers", headers, 0);
> +    av_opt_set(h->priv_data, "method", "POST", 0);
> +    av_opt_set_bin(h->priv_data, "post_data", (uint8_t*)offer_sdp, strlen(offer_sdp), 0);
> +
> +    /* open the http context */
> +    if ((ret = ffurl_connect(h, NULL)) < 0) {
> +        av_log(ctx->avctx, AV_LOG_ERROR, "ffurl_connect failed\n");
> +        goto fail;
> +    }
> +
> +    /* read the server reply */
> +    ret = ffurl_read_complete(h, (unsigned char*)response_sdp, sizeof(response_sdp));
> +    if (ret < 0) {
> +        av_log(ctx->avctx, AV_LOG_ERROR, "ffurl_read_complete failed\n");
> +        goto fail;
> +    }
> +
> +    av_log(ctx->avctx, AV_LOG_VERBOSE, "response: %s\n", response_sdp);
> +
> +    /* set remote description */
> +    ret = rtcSetRemoteDescription(ctx->peer_connection, response_sdp, "answer");
> +    if (ret < 0) {
> +        av_log(ctx->avctx, AV_LOG_ERROR, "Failed to set remote description\n");
> +        goto fail;
> +    }
> +
> +    /* save resource location for later use */
> +    av_opt_get(h->priv_data, "new_location", AV_OPT_SEARCH_CHILDREN, (uint8_t**)&ctx->resource_location);
> +    av_log(ctx->avctx, AV_LOG_VERBOSE, "resource_location: %s\n", ctx->resource_location);
> +
> +    /* close the http context */
> +    if ((ret = ffurl_closep(&h)) < 0) {
> +        av_log(ctx->avctx, AV_LOG_ERROR, "ffurl_closep failed\n");
> +        goto fail;
> +    }
> +
> +    av_freep(&headers);
> +    return 0;
> +
> +fail:
> +    if (h) {
> +        ffurl_closep(&h);
> +    }
> +    av_freep(&headers);
> +    return ret;
> +}
> +
> +int webrtc_close_resource(DataChannelContext*const ctx)
> +{
> +    int ret;
> +    URLContext* h = NULL;
> +    char* headers = NULL;
> +
> +    if (!ctx->resource_location) {
> +        return 0;
> +    }
> +
> +    /* alloc the http context */
> +    if ((ret = ffurl_alloc(&h, ctx->resource_location, AVIO_FLAG_READ_WRITE, NULL)) < 0) {
> +        av_log(ctx->avctx, AV_LOG_ERROR, "ffurl_alloc failed\n");
> +        goto fail;
> +    }
> +
> +    /* set options */
> +    if (ctx->bearer_token) {
> +        headers = av_asprintf("Authorization: Bearer %s\r\n", ctx->bearer_token);

Should check that "headers" is non-NULL (i.e. that we're not out of memory)

> +        av_log(ctx->avctx, AV_LOG_VERBOSE, "headers: %s\n", headers);
> +    }
> +    av_opt_set(h->priv_data, "method", "DELETE", 0);
> +
> +    /* open the http context */
> +    if ((ret = ffurl_connect(h, NULL)) < 0) {
> +        av_log(ctx->avctx, AV_LOG_ERROR, "ffurl_connect failed\n");
> +        goto fail;
> +    }
> +
> +    /* close the http context */
> +    if ((ret = ffurl_closep(&h)) < 0) {
> +        av_log(ctx->avctx, AV_LOG_ERROR, "ffurl_close failed\n");
> +        goto fail;
> +    }
> +
> +fail:
> +    if (h) {
> +        ffurl_closep(&h);
> +    }
> +    av_freep(&ctx->resource_location);
> +    av_freep(&headers);
> +    return ret;
> +}
> +
> +/* callback for receiving data */
> +static int webrtc_read(URLContext *h, unsigned char *buf, int size)
> +{
> +    const DataChannelTrack*const ctx = (const DataChannelTrack*const)h->priv_data;
> +    int ret;
> +
> +    ret = rtcReceiveMessage(ctx->track_id, (char*)buf, &size);
> +    if (ret == RTC_ERR_NOT_AVAIL) {
> +        return AVERROR(EAGAIN);
> +    }
> +    else if (ret == RTC_ERR_TOO_SMALL) {
> +        return AVERROR_BUFFER_TOO_SMALL;
> +    }
> +    else if (ret != RTC_ERR_SUCCESS) {
> +        av_log(ctx->avctx, AV_LOG_ERROR, "rtcReceiveMessage failed: %d\n", ret);
> +        return AVERROR_EOF;
> +    }
> +    return size;
> +}
> +
> +/* callback for sending data */
> +static int webrtc_write(URLContext *h, const unsigned char *buf, int size)
> +{
> +    const DataChannelTrack*const ctx = (const DataChannelTrack*const)h->priv_data;
> +    int ret;
> +
> +    ret = rtcSendMessage(ctx->track_id, (const char*)buf, size);
> +    if (ret != RTC_ERR_SUCCESS) {
> +        av_log(ctx->avctx, AV_LOG_ERROR, "rtcSendMessage failed: %d\n", ret);
> +        return AVERROR_EXTERNAL;
> +    }
> +    return size;
> +}
> +
> +static const URLProtocol ff_webrtc_protocol = {
> +    .name            = "webrtc",
> +    .url_read        = webrtc_read,
> +    .url_write       = webrtc_write,
> +};
> +
> +int webrtc_init_urlcontext(DataChannelContext*const ctx, int track_idx)
> +{
> +    DataChannelTrack*const track = &ctx->tracks[track_idx];
> +
> +    track->rtp_url_context = av_mallocz(sizeof(URLContext));
> +    if (!track->rtp_url_context) {
> +        return AVERROR(ENOMEM);
> +    }
> +
> +    track->rtp_url_context->prot = &ff_webrtc_protocol;
> +    track->rtp_url_context->priv_data = track;
> +    track->rtp_url_context->max_packet_size = RTP_MAX_PACKET_SIZE;
> +    track->rtp_url_context->flags = AVIO_FLAG_READ_WRITE;
> +    track->rtp_url_context->rw_timeout = ctx->rw_timeout;
> +    return 0;
> +}
> +
> +static void webrtc_on_state_change(int pc, rtcState state, void* ptr)
> +{
> +    DataChannelContext*const ctx = (DataChannelContext*const)ptr;
> +
> +    av_log(ctx->avctx, AV_LOG_VERBOSE, "Connection state changed from %s to %s\n", webrtc_get_state_name(ctx->state), webrtc_get_state_name(state));
> +    ctx->state = state;
> +}
> +
> +int webrtc_init_connection(DataChannelContext *const ctx)
> +{
> +    int ret;
> +    rtcConfiguration config = { 0 };
> +
> +    if (!(ctx->peer_connection = rtcCreatePeerConnection(&config))) {
> +        av_log(ctx->avctx, AV_LOG_ERROR, "Failed to create PeerConnection\n");
> +        return AVERROR_EXTERNAL;
> +    }
> +
> +    rtcSetUserPointer(ctx->peer_connection, ctx);
> +
> +    if (rtcSetStateChangeCallback(ctx->peer_connection, webrtc_on_state_change)) {
> +        av_log(ctx->avctx, AV_LOG_ERROR, "Failed to set state change callback\n");
> +        ret = AVERROR_EXTERNAL;
> +        goto fail;
> +    }
> +
> +    return 0;
> +
> +fail:
> +    rtcDeletePeerConnection(ctx->peer_connection);
> +    return ret;
> +}
> +
> +int webrtc_convert_codec(enum AVCodecID codec_id, rtcCodec* rtc_codec)
> +{
> +    switch (codec_id)
> +    {
> +        case AV_CODEC_ID_H264:
> +            *rtc_codec = RTC_CODEC_H264;
> +            break;
> +        case AV_CODEC_ID_HEVC:
> +            *rtc_codec = RTC_CODEC_H265;
> +            break;
> +        case AV_CODEC_ID_AV1:
> +            *rtc_codec = RTC_CODEC_AV1;
> +            break;
> +        case AV_CODEC_ID_VP9:
> +            *rtc_codec = RTC_CODEC_VP9;
> +            break;
> +        case AV_CODEC_ID_OPUS:
> +            *rtc_codec = RTC_CODEC_OPUS;
> +            break;
> +        case AV_CODEC_ID_AAC:
> +            *rtc_codec = RTC_CODEC_AAC;
> +            break;
> +        case AV_CODEC_ID_PCM_ALAW:
> +            *rtc_codec = RTC_CODEC_PCMA;
> +            break;
> +        case AV_CODEC_ID_PCM_MULAW:
> +            *rtc_codec = RTC_CODEC_PCMU;
> +            break;
> +        default:
> +            *rtc_codec = -1;
> +            return AVERROR(EINVAL);
> +    }
> +
> +    return 0;
> +}
> +

No VP8?

> +void webrtc_deinit(DataChannelContext*const ctx)
> +{
> +    if (ctx->tracks) {
> +        for (int i = 0; i < ctx->nb_tracks; ++i) {
> +            if (ctx->tracks[i].rtp_ctx)
> +                avformat_free_context(ctx->tracks[i].rtp_ctx);
> +            if (ctx->tracks[i].rtp_url_context)
> +                av_freep(&ctx->tracks[i].rtp_url_context);
> +            if (ctx->tracks[i].track_id)
> +                rtcDeleteTrack(ctx->tracks[i].track_id);
> +        }
> +        av_freep(&ctx->tracks);
> +    }
> +    if (ctx->peer_connection) {
> +        rtcDeletePeerConnection(ctx->peer_connection);
> +        ctx->peer_connection = 0;
> +    }
> +    if (ctx->resource_location)
> +        av_freep(&ctx->resource_location);
> +}
> \ No newline at end of file
> diff --git a/libavformat/webrtc.h b/libavformat/webrtc.h
> new file mode 100644
> index 00000000000..f7d81f3dd0b
> --- /dev/null
> +++ b/libavformat/webrtc.h
> @@ -0,0 +1,70 @@
> +/*
> + * WebRTC-HTTP ingestion/egress protocol (WHIP/WHEP) common code
> + *
> + * Copyright (C) 2023 NativeWaves GmbH <contact@nativewaves.com>
> + * This work is supported by FFG project 47168763.
> + *
> + * This file is part of FFmpeg.
> + *
> + * FFmpeg is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU Lesser General Public
> + * License as published by the Free Software Foundation; either
> + * version 2.1 of the License, or (at your option) any later version.
> + *
> + * FFmpeg is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> + * Lesser General Public License for more details.
> + *
> + * You should have received a copy of the GNU Lesser General Public
> + * License along with FFmpeg; if not, write to the Free Software Foundation,
> + * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
> + */
> +
> +#ifndef AVFORMAT_WEBRTC_H
> +#define AVFORMAT_WEBRTC_H
> +
> +#include "avformat.h"
> +#include "avio_internal.h"
> +#include "libavcodec/codec_id.h"
> +#include "url.h"
> +#include "rtc/rtc.h"
> +
> +#define RTP_MAX_PACKET_SIZE 1450
> +
> +typedef struct DataChannelTrack {
> +    AVFormatContext *avctx;
> +    int track_id;
> +    AVFormatContext *rtp_ctx;
> +    URLContext *rtp_url_context;
> +} DataChannelTrack;
> +
> +typedef struct DataChannelContext {
> +    AVFormatContext *avctx;
> +    int peer_connection;
> +    rtcState state;
> +    DataChannelTrack *tracks;
> +    int nb_tracks;
> +    const char *resource_location;
> +
> +    /* options */
> +    char* bearer_token;
> +    int64_t connection_timeout;
> +    int64_t rw_timeout;
> +} DataChannelContext;
> +
> +#define WEBRTC_OPTIONS(FLAGS, offset) \
> +    { "bearer_token", "optional Bearer token for authentication and authorization", offset+offsetof(DataChannelContext, bearer_token), AV_OPT_TYPE_STRING, { .str = NULL }, 0, 0, FLAGS }, \

nit: is the capitalization on "Bearer" intended?

> +    { "connection_timeout", "timeout for establishing a connection", offset+offsetof(DataChannelContext, connection_timeout), AV_OPT_TYPE_DURATION, { .i64 = 10000000 }, 1, INT_MAX, FLAGS }, \
> +    { "rw_timeout", "timeout for receiving/writing data", offset+offsetof(DataChannelContext, rw_timeout), AV_OPT_TYPE_DURATION, { .i64 = 1000000 }, 1, INT_MAX, FLAGS }
> +
> +extern int webrtc_close_resource(DataChannelContext*const ctx);
> +extern int webrtc_convert_codec(enum AVCodecID codec_id, rtcCodec* rtc_codec);
> +extern int webrtc_create_resource(DataChannelContext*const ctx);
> +extern void webrtc_deinit(DataChannelContext*const ctx);
> +extern int webrtc_generate_media_stream_id(char media_stream_id[37]);
> +extern int webrtc_init_connection(DataChannelContext*const ctx);
> +extern void webrtc_init_logger(void);
> +extern int webrtc_init_urlcontext(DataChannelContext*const ctx, int track_idx);
> +
> +#endif /* AVFORMAT_WEBRTC_H */
> --
> 2.39.2
>
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I'll try to properly test and give some more in-depth feedback but
overall this looks pretty nice (previously I'd been testing this kind
of thing with https://github.com/ggarber/whip-go and OBS).

Best,
-t

On 06.11.2023 16:19, Michael Riedl wrote:
> Signed-off-by: Michael Riedl <michael.riedl@nativewaves.com>
> ---
>   libavformat/webrtc.c | 398 +++++++++++++++++++++++++++++++++++++++++++
>   libavformat/webrtc.h |  70 ++++++++
>   2 files changed, 468 insertions(+)
>   create mode 100644 libavformat/webrtc.c
>   create mode 100644 libavformat/webrtc.h
> 
> diff --git a/libavformat/webrtc.c b/libavformat/webrtc.c
> new file mode 100644
> index 00000000000..75884eac46f
> --- /dev/null
> +++ b/libavformat/webrtc.c
> @@ -0,0 +1,398 @@
> +/*
> + * WebRTC-HTTP ingestion/egress protocol (WHIP/WHEP) common code
> + *
> + * Copyright (C) 2023 NativeWaves GmbH <contact@nativewaves.com>
> + * This work is supported by FFG project 47168763.
> + *
> + * This file is part of FFmpeg.
> + *
> + * FFmpeg is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU Lesser General Public
> + * License as published by the Free Software Foundation; either
> + * version 2.1 of the License, or (at your option) any later version.
> + *
> + * FFmpeg is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> + * Lesser General Public License for more details.
> + *
> + * You should have received a copy of the GNU Lesser General Public
> + * License along with FFmpeg; if not, write to the Free Software Foundation,
> + * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
> + */
> +
> +#include "libavutil/avstring.h"
> +#include "libavutil/opt.h"
> +#include "libavutil/uuid.h"
> +#include "libavutil/random_seed.h"
> +#include "rtpenc_chain.h"
> +#include "rtsp.h"
> +#include "webrtc.h"
> +
> +static const char* webrtc_get_state_name(const rtcState state)
> +{
> +    switch (state)
> +    {
> +        case RTC_NEW:
> +            return "RTC_NEW";
> +        case RTC_CONNECTING:
> +            return "RTC_CONNECTING";
> +        case RTC_CONNECTED:
> +            return "RTC_CONNECTED";
> +        case RTC_DISCONNECTED:
> +            return "RTC_DISCONNECTED";
> +        case RTC_FAILED:
> +            return "RTC_FAILED";
> +        case RTC_CLOSED:
> +            return "RTC_CLOSED";
> +        default:
> +            return "UNKNOWN";
> +    }
> +}
> +
> +static void webrtc_log(const rtcLogLevel rtcLevel, const char *const message)
> +{
> +    int level = AV_LOG_VERBOSE;
> +    switch (rtcLevel)
> +    {
> +        case RTC_LOG_NONE:
> +            level = AV_LOG_QUIET;
> +            break;
> +        case RTC_LOG_DEBUG:
> +        case RTC_LOG_VERBOSE:
> +            level = AV_LOG_DEBUG;
> +            break;
> +        case RTC_LOG_INFO:
> +            level = AV_LOG_VERBOSE;
> +            break;
> +        case RTC_LOG_WARNING:
> +            level = AV_LOG_WARNING;
> +            break;
> +        case RTC_LOG_ERROR:
> +            level = AV_LOG_ERROR;
> +            break;
> +        case RTC_LOG_FATAL:
> +            level = AV_LOG_FATAL;
> +            break;
> +    }
> +
> +    av_log(NULL, level, "[libdatachannel] %s\n", message);
> +}
> +
> +void webrtc_init_logger(void)
> +{
> +    rtcLogLevel level = RTC_LOG_VERBOSE;
> +    switch (av_log_get_level())
> +    {
> +        case AV_LOG_QUIET:
> +            level = RTC_LOG_NONE;
> +            break;
> +        case AV_LOG_DEBUG:
> +            level = RTC_LOG_DEBUG;
> +            break;
> +        case AV_LOG_VERBOSE:
> +            level = RTC_LOG_VERBOSE;
> +            break;
> +        case AV_LOG_WARNING:
> +            level = RTC_LOG_WARNING;
> +            break;
> +        case AV_LOG_ERROR:
> +            level = RTC_LOG_ERROR;
> +            break;
> +        case AV_LOG_FATAL:
> +            level = RTC_LOG_FATAL;
> +            break;
> +    }
> +
> +    rtcInitLogger(level, webrtc_log);
> +}
> +
> +int webrtc_generate_media_stream_id(char media_stream_id[37])
> +{
> +    int ret;
> +    AVUUID uuid;
> +
> +    ret = av_random_bytes(uuid, sizeof(uuid));
> +    if (ret < 0) {
> +        goto fail;
> +    }
> +    av_uuid_unparse(uuid, media_stream_id);
> +    return 0;
> +
> +fail:
> +    return ret;
> +}
> +
> +int webrtc_create_resource(DataChannelContext*const ctx)
> +{
> +    int ret;
> +    URLContext* h = NULL;
> +    char* headers;
> +    char offer_sdp[SDP_MAX_SIZE] = { 0 };
> +    char response_sdp[SDP_MAX_SIZE] = { 0 };
> +
> +    /* set local description */
> +    if (rtcSetLocalDescription(ctx->peer_connection, "offer") != RTC_ERR_SUCCESS) {
> +        av_log(ctx->avctx, AV_LOG_ERROR, "Failed to set local description\n");
> +        ret = AVERROR_EXTERNAL;
> +        goto fail;
> +    }
> +
> +    /* create offer */
> +    ret = rtcGetLocalDescription(ctx->peer_connection, offer_sdp, sizeof(offer_sdp));
> +    if (ret < 0) {
> +        av_log(ctx->avctx, AV_LOG_ERROR, "Failed to get local description\n");
> +        ret = AVERROR_EXTERNAL;
> +        goto fail;
> +    }
> +    av_log(ctx->avctx, AV_LOG_VERBOSE, "offer_sdp: %s\n", offer_sdp);
> +
> +    /* alloc the http context */
> +    if ((ret = ffurl_alloc(&h, ctx->avctx->url, AVIO_FLAG_READ_WRITE, NULL)) < 0) {
> +        av_log(ctx->avctx, AV_LOG_ERROR, "ffurl_alloc failed\n");
> +        goto fail;
> +    }
> +
> +    /* set options */
> +    headers = av_asprintf("Content-type: application/sdp\r\n");
> +    if (ctx->bearer_token) {
> +        headers = av_asprintf("%sAuthorization: Bearer %s\r\n", headers, ctx->bearer_token);
> +    }
> +    av_log(ctx->avctx, AV_LOG_VERBOSE, "headers: %s\n", headers);
> +    av_opt_set(h->priv_data, "headers", headers, 0);
> +    av_opt_set(h->priv_data, "method", "POST", 0);
> +    av_opt_set_bin(h->priv_data, "post_data", (uint8_t*)offer_sdp, strlen(offer_sdp), 0);
> +
> +    /* open the http context */
> +    if ((ret = ffurl_connect(h, NULL)) < 0) {
> +        av_log(ctx->avctx, AV_LOG_ERROR, "ffurl_connect failed\n");
> +        goto fail;
> +    }
> +
> +    /* read the server reply */
> +    ret = ffurl_read_complete(h, (unsigned char*)response_sdp, sizeof(response_sdp));
> +    if (ret < 0) {
> +        av_log(ctx->avctx, AV_LOG_ERROR, "ffurl_read_complete failed\n");
> +        goto fail;
> +    }
> +
> +    av_log(ctx->avctx, AV_LOG_VERBOSE, "response: %s\n", response_sdp);
> +
> +    /* set remote description */
> +    ret = rtcSetRemoteDescription(ctx->peer_connection, response_sdp, "answer");
> +    if (ret < 0) {
> +        av_log(ctx->avctx, AV_LOG_ERROR, "Failed to set remote description\n");
> +        goto fail;
> +    }
> +
> +    /* save resource location for later use */
> +    av_opt_get(h->priv_data, "new_location", AV_OPT_SEARCH_CHILDREN, (uint8_t**)&ctx->resource_location);
> +    av_log(ctx->avctx, AV_LOG_VERBOSE, "resource_location: %s\n", ctx->resource_location);
> +
> +    /* close the http context */
> +    if ((ret = ffurl_closep(&h)) < 0) {
> +        av_log(ctx->avctx, AV_LOG_ERROR, "ffurl_closep failed\n");
> +        goto fail;
> +    }
> +
> +    av_freep(&headers);
> +    return 0;
> +
> +fail:
> +    if (h) {
> +        ffurl_closep(&h);
> +    }
> +    av_freep(&headers);
> +    return ret;
> +}
> +
> +int webrtc_close_resource(DataChannelContext*const ctx)
> +{
> +    int ret;
> +    URLContext* h = NULL;
> +    char* headers = NULL;
> +
> +    if (!ctx->resource_location) {
> +        return 0;
> +    }
> +
> +    /* alloc the http context */
> +    if ((ret = ffurl_alloc(&h, ctx->resource_location, AVIO_FLAG_READ_WRITE, NULL)) < 0) {
> +        av_log(ctx->avctx, AV_LOG_ERROR, "ffurl_alloc failed\n");
> +        goto fail;
> +    }
> +
> +    /* set options */
> +    if (ctx->bearer_token) {
> +        headers = av_asprintf("Authorization: Bearer %s\r\n", ctx->bearer_token);
> +        av_log(ctx->avctx, AV_LOG_VERBOSE, "headers: %s\n", headers);
> +    }
> +    av_opt_set(h->priv_data, "method", "DELETE", 0);
> +
> +    /* open the http context */
> +    if ((ret = ffurl_connect(h, NULL)) < 0) {
> +        av_log(ctx->avctx, AV_LOG_ERROR, "ffurl_connect failed\n");
> +        goto fail;
> +    }
> +
> +    /* close the http context */
> +    if ((ret = ffurl_closep(&h)) < 0) {
> +        av_log(ctx->avctx, AV_LOG_ERROR, "ffurl_close failed\n");
> +        goto fail;
> +    }
> +
> +fail:
> +    if (h) {
> +        ffurl_closep(&h);
> +    }
> +    av_freep(&ctx->resource_location);
> +    av_freep(&headers);
> +    return ret;
> +}
> +
> +/* callback for receiving data */
> +static int webrtc_read(URLContext *h, unsigned char *buf, int size)
> +{
> +    const DataChannelTrack*const ctx = (const DataChannelTrack*const)h->priv_data;
> +    int ret;
> +
> +    ret = rtcReceiveMessage(ctx->track_id, (char*)buf, &size);
> +    if (ret == RTC_ERR_NOT_AVAIL) {
> +        return AVERROR(EAGAIN);
> +    }
> +    else if (ret == RTC_ERR_TOO_SMALL) {
> +        return AVERROR_BUFFER_TOO_SMALL;
> +    }
> +    else if (ret != RTC_ERR_SUCCESS) {
> +        av_log(ctx->avctx, AV_LOG_ERROR, "rtcReceiveMessage failed: %d\n", ret);
> +        return AVERROR_EOF;
> +    }
> +    return size;
> +}
> +
> +/* callback for sending data */
> +static int webrtc_write(URLContext *h, const unsigned char *buf, int size)
> +{
> +    const DataChannelTrack*const ctx = (const DataChannelTrack*const)h->priv_data;
> +    int ret;
> +
> +    ret = rtcSendMessage(ctx->track_id, (const char*)buf, size);
> +    if (ret != RTC_ERR_SUCCESS) {
> +        av_log(ctx->avctx, AV_LOG_ERROR, "rtcSendMessage failed: %d\n", ret);
> +        return AVERROR_EXTERNAL;
> +    }
> +    return size;
> +}
> +
> +static const URLProtocol ff_webrtc_protocol = {
> +    .name            = "webrtc",
> +    .url_read        = webrtc_read,
> +    .url_write       = webrtc_write,
> +};
> +
> +int webrtc_init_urlcontext(DataChannelContext*const ctx, int track_idx)
> +{
> +    DataChannelTrack*const track = &ctx->tracks[track_idx];
> +
> +    track->rtp_url_context = av_mallocz(sizeof(URLContext));
> +    if (!track->rtp_url_context) {
> +        return AVERROR(ENOMEM);
> +    }
> +
> +    track->rtp_url_context->prot = &ff_webrtc_protocol;
> +    track->rtp_url_context->priv_data = track;
> +    track->rtp_url_context->max_packet_size = RTP_MAX_PACKET_SIZE;
> +    track->rtp_url_context->flags = AVIO_FLAG_READ_WRITE;
> +    track->rtp_url_context->rw_timeout = ctx->rw_timeout;
> +    return 0;
> +}
> +
> +static void webrtc_on_state_change(int pc, rtcState state, void* ptr)
> +{
> +    DataChannelContext*const ctx = (DataChannelContext*const)ptr;
> +
> +    av_log(ctx->avctx, AV_LOG_VERBOSE, "Connection state changed from %s to %s\n", webrtc_get_state_name(ctx->state), webrtc_get_state_name(state));
> +    ctx->state = state;
> +}
> +
> +int webrtc_init_connection(DataChannelContext *const ctx)
> +{
> +    int ret;
> +    rtcConfiguration config = { 0 };
> +
> +    if (!(ctx->peer_connection = rtcCreatePeerConnection(&config))) {
> +        av_log(ctx->avctx, AV_LOG_ERROR, "Failed to create PeerConnection\n");
> +        return AVERROR_EXTERNAL;
> +    }
> +
> +    rtcSetUserPointer(ctx->peer_connection, ctx);
> +
> +    if (rtcSetStateChangeCallback(ctx->peer_connection, webrtc_on_state_change)) {
> +        av_log(ctx->avctx, AV_LOG_ERROR, "Failed to set state change callback\n");
> +        ret = AVERROR_EXTERNAL;
> +        goto fail;
> +    }
> +
> +    return 0;
> +
> +fail:
> +    rtcDeletePeerConnection(ctx->peer_connection);
> +    return ret;
> +}
> +
> +int webrtc_convert_codec(enum AVCodecID codec_id, rtcCodec* rtc_codec)
> +{
> +    switch (codec_id)
> +    {
> +        case AV_CODEC_ID_H264:
> +            *rtc_codec = RTC_CODEC_H264;
> +            break;
> +        case AV_CODEC_ID_HEVC:
> +            *rtc_codec = RTC_CODEC_H265;
> +            break;
> +        case AV_CODEC_ID_AV1:
> +            *rtc_codec = RTC_CODEC_AV1;
> +            break;
> +        case AV_CODEC_ID_VP9:
> +            *rtc_codec = RTC_CODEC_VP9;
> +            break;
> +        case AV_CODEC_ID_OPUS:
> +            *rtc_codec = RTC_CODEC_OPUS;
> +            break;
> +        case AV_CODEC_ID_AAC:
> +            *rtc_codec = RTC_CODEC_AAC;
> +            break;
> +        case AV_CODEC_ID_PCM_ALAW:
> +            *rtc_codec = RTC_CODEC_PCMA;
> +            break;
> +        case AV_CODEC_ID_PCM_MULAW:
> +            *rtc_codec = RTC_CODEC_PCMU;
> +            break;
> +        default:
> +            *rtc_codec = -1;
> +            return AVERROR(EINVAL);
> +    }
> +
> +    return 0;
> +}
> +
> +void webrtc_deinit(DataChannelContext*const ctx)
> +{
> +    if (ctx->tracks) {
> +        for (int i = 0; i < ctx->nb_tracks; ++i) {
> +            if (ctx->tracks[i].rtp_ctx)
> +                avformat_free_context(ctx->tracks[i].rtp_ctx);
> +            if (ctx->tracks[i].rtp_url_context)
> +                av_freep(&ctx->tracks[i].rtp_url_context);
> +            if (ctx->tracks[i].track_id)
> +                rtcDeleteTrack(ctx->tracks[i].track_id);
> +        }
> +        av_freep(&ctx->tracks);
> +    }
> +    if (ctx->peer_connection) {
> +        rtcDeletePeerConnection(ctx->peer_connection);
> +        ctx->peer_connection = 0;
> +    }
> +    if (ctx->resource_location)
> +        av_freep(&ctx->resource_location);
> +}
> \ No newline at end of file
> diff --git a/libavformat/webrtc.h b/libavformat/webrtc.h
> new file mode 100644
> index 00000000000..f7d81f3dd0b
> --- /dev/null
> +++ b/libavformat/webrtc.h
> @@ -0,0 +1,70 @@
> +/*
> + * WebRTC-HTTP ingestion/egress protocol (WHIP/WHEP) common code
> + *
> + * Copyright (C) 2023 NativeWaves GmbH <contact@nativewaves.com>
> + * This work is supported by FFG project 47168763.
> + *
> + * This file is part of FFmpeg.
> + *
> + * FFmpeg is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU Lesser General Public
> + * License as published by the Free Software Foundation; either
> + * version 2.1 of the License, or (at your option) any later version.
> + *
> + * FFmpeg is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> + * Lesser General Public License for more details.
> + *
> + * You should have received a copy of the GNU Lesser General Public
> + * License along with FFmpeg; if not, write to the Free Software Foundation,
> + * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
> + */
> +
> +#ifndef AVFORMAT_WEBRTC_H
> +#define AVFORMAT_WEBRTC_H
> +
> +#include "avformat.h"
> +#include "avio_internal.h"
> +#include "libavcodec/codec_id.h"
> +#include "url.h"
> +#include "rtc/rtc.h"
> +
> +#define RTP_MAX_PACKET_SIZE 1450
> +
> +typedef struct DataChannelTrack {
> +    AVFormatContext *avctx;
> +    int track_id;
> +    AVFormatContext *rtp_ctx;
> +    URLContext *rtp_url_context;
> +} DataChannelTrack;
> +
> +typedef struct DataChannelContext {
> +    AVFormatContext *avctx;
> +    int peer_connection;
> +    rtcState state;
> +    DataChannelTrack *tracks;
> +    int nb_tracks;
> +    const char *resource_location;
> +
> +    /* options */
> +    char* bearer_token;
> +    int64_t connection_timeout;
> +    int64_t rw_timeout;
> +} DataChannelContext;
> +
> +#define WEBRTC_OPTIONS(FLAGS, offset) \
> +    { "bearer_token", "optional Bearer token for authentication and authorization", offset+offsetof(DataChannelContext, bearer_token), AV_OPT_TYPE_STRING, { .str = NULL }, 0, 0, FLAGS }, \
> +    { "connection_timeout", "timeout for establishing a connection", offset+offsetof(DataChannelContext, connection_timeout), AV_OPT_TYPE_DURATION, { .i64 = 10000000 }, 1, INT_MAX, FLAGS }, \
> +    { "rw_timeout", "timeout for receiving/writing data", offset+offsetof(DataChannelContext, rw_timeout), AV_OPT_TYPE_DURATION, { .i64 = 1000000 }, 1, INT_MAX, FLAGS }
> +
> +extern int webrtc_close_resource(DataChannelContext*const ctx);
> +extern int webrtc_convert_codec(enum AVCodecID codec_id, rtcCodec* rtc_codec);
> +extern int webrtc_create_resource(DataChannelContext*const ctx);
> +extern void webrtc_deinit(DataChannelContext*const ctx);
> +extern int webrtc_generate_media_stream_id(char media_stream_id[37]);
> +extern int webrtc_init_connection(DataChannelContext*const ctx);
> +extern void webrtc_init_logger(void);
> +extern int webrtc_init_urlcontext(DataChannelContext*const ctx, int track_idx);

You should look at how other headers for internal functions do stuff.
All functions and structs need appropiate prefixes.

And I'm also not sure that options-define is how we do things. I'm not 
even sure how to use it properly on first glance.

> +#endif /* AVFORMAT_WEBRTC_H */