[FFmpeg-devel,v2,5/5] avformat: add amv muxer

AMV is a hard-coded (and broken) subset of AVI. It's not worth sullying
the existing AVI muxer with its filth.

Fixes ticket #747.

Signed-off-by: Zane van Iperen <zane@zanevaniperen.com>
---
 MAINTAINERS              |   1 +
 libavformat/Makefile     |   1 +
 libavformat/allformats.c |   1 +
 libavformat/amvenc.c     | 414 +++++++++++++++++++++++++++++++++++++++
 4 files changed, 417 insertions(+)
 create mode 100644 libavformat/amvenc.c

Zane van Iperen:
> AMV is a hard-coded (and broken) subset of AVI. It's not worth sullying
> the existing AVI muxer with its filth.
> 
> Fixes ticket #747.
> 
> Signed-off-by: Zane van Iperen <zane@zanevaniperen.com>
> ---
>  MAINTAINERS              |   1 +
>  libavformat/Makefile     |   1 +
>  libavformat/allformats.c |   1 +
>  libavformat/amvenc.c     | 414 +++++++++++++++++++++++++++++++++++++++
>  4 files changed, 417 insertions(+)
>  create mode 100644 libavformat/amvenc.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 7a4161e2e5..2464f82be3 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -394,6 +394,7 @@ Muxers/Demuxers:
>    aiffdec.c                             Baptiste Coudurier, Matthieu Bouron
>    aiffenc.c                             Baptiste Coudurier, Matthieu Bouron
>    alp.c                                 Zane van Iperen
> +  amvenc.c                              Zane van Iperen
>    apm.c                                 Zane van Iperen
>    apngdec.c                             Benoit Fouet
>    argo_asf.c                            Zane van Iperen
> diff --git a/libavformat/Makefile b/libavformat/Makefile
> index 25bb8b2c69..be5a482b01 100644
> --- a/libavformat/Makefile
> +++ b/libavformat/Makefile
> @@ -93,6 +93,7 @@ OBJS-$(CONFIG_AMR_DEMUXER)               += amr.o
>  OBJS-$(CONFIG_AMR_MUXER)                 += amr.o rawenc.o
>  OBJS-$(CONFIG_AMRNB_DEMUXER)             += amr.o
>  OBJS-$(CONFIG_AMRWB_DEMUXER)             += amr.o
> +OBJS-$(CONFIG_AMV_MUXER)                 += amvenc.o
>  OBJS-$(CONFIG_ANM_DEMUXER)               += anm.o
>  OBJS-$(CONFIG_APC_DEMUXER)               += apc.o
>  OBJS-$(CONFIG_APE_DEMUXER)               += ape.o apetag.o img2.o
> diff --git a/libavformat/allformats.c b/libavformat/allformats.c
> index 9b1b611a49..53e5374255 100644
> --- a/libavformat/allformats.c
> +++ b/libavformat/allformats.c
> @@ -54,6 +54,7 @@ extern AVInputFormat  ff_amr_demuxer;
>  extern AVOutputFormat ff_amr_muxer;
>  extern AVInputFormat  ff_amrnb_demuxer;
>  extern AVInputFormat  ff_amrwb_demuxer;
> +extern AVOutputFormat ff_amv_muxer;
>  extern AVInputFormat  ff_anm_demuxer;
>  extern AVInputFormat  ff_apc_demuxer;
>  extern AVInputFormat  ff_ape_demuxer;
> diff --git a/libavformat/amvenc.c b/libavformat/amvenc.c
> new file mode 100644
> index 0000000000..ea5fc2a0f9
> --- /dev/null
> +++ b/libavformat/amvenc.c
> @@ -0,0 +1,414 @@
> +/*
> + * AMV muxer
> + *
> + * Copyright (C) 2020 Zane van Iperen (zane@zanevaniperen.com)
> + *
> + * 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 "avformat.h"
> +#include "riff.h"
> +#include "internal.h"
> +#include "avio_internal.h"
> +#include "libavutil/intreadwrite.h"
> +#include "libavutil/avassert.h"
> +
> +/*
> + * Things to note:
> + * - AMV is a hard-coded (and broken) subset of AVI. It's not worth sullying the
> + *   existing AVI muxer with its filth.
> + * - No separate demuxer as the existing AVI demuxer can handle these.
> + * - The sizes of certain tags are deliberately set to 0 as some players break
> + *   when they're set correctly. Ditto with some header fields.
> + * - There is no index.
> + * - Players are **very** sensitive to the frame order and sizes.
> + *   - Frames must be strictly interleaved as V-A, any V-V or A-A will
> + *     cause crashes.
> + *   - Variable video frame sizes seem to be handled fine.
> + *   - Variable audio frame sizes cause crashes.
> + *   - If audio is shorter than video, it's padded with silence.
> + *   - If video is shorter than audio, the most recent frame is repeated.
> + */
> +
> +#define AMV_STREAM_COUNT     2
> +#define AMV_STREAM_VIDEO     0
> +#define AMV_STREAM_AUDIO     1
> +#define AMV_VIDEO_STRH_SIZE 56
> +#define AMV_VIDEO_STRF_SIZE 36
> +#define AMV_AUDIO_STRH_SIZE 48
> +#define AMV_AUDIO_STRF_SIZE 20 /* sizeof(WAVEFORMATEX) + 2 */
> +
> +typedef struct AMVContext
> +{
> +    int64_t riff_start;
> +    int64_t movi_list;
> +    int64_t offset_duration;
> +    int     last_stream;
> +
> +    int32_t us_per_frame; /* Microseconds per frame.         */
> +
> +    int32_t aframe_size;  /* Expected audio frame size.      */
> +    int32_t ablock_align; /* Expected audio block align.     */
> +    AVPacket apad;        /* Dummy audio packet for padding. */
> +    AVPacket vpad;        /* Most recent video frame, for padding. */
> +
> +    /*
> +     * Cumulative PTS values for each stream, used for the final
> +     * duration calculcation.
> +     */
> +    int64_t lastpts[AMV_STREAM_COUNT];
> +} AMVContext;
> +
> +/* ff_{start,end}_tag(), but sets the size to 0. */
> +static int64_t amv_start_tag(AVIOContext *pb, const char *tag)
> +{
> +    ffio_wfourcc(pb, tag);
> +    avio_wl32(pb, 0);
> +    return avio_tell(pb);
> +}
> +
> +static void amv_end_tag(AVIOContext *pb, int64_t start)
> +{
> +    int64_t pos;
> +    av_assert0((start&1) == 0);
> +
> +    pos = avio_tell(pb);
> +    if (pos & 1)
> +        avio_w8(pb, 0);
> +}
> +
> +static av_cold int amv_init(AVFormatContext *s)
> +{
> +    AMVContext *amv = s->priv_data;
> +    AVStream   *vst, *ast;
> +    int ret;
> +
> +    amv->last_stream  = -1;
> +
> +    if (s->nb_streams != AMV_STREAM_COUNT) {
> +        av_log(s, AV_LOG_ERROR, "AMV files only support 2 streams\n");
> +        return AVERROR(EINVAL);
> +    }
> +
> +    vst = s->streams[AMV_STREAM_VIDEO];
> +    ast = s->streams[AMV_STREAM_AUDIO];
> +
> +    if (vst->codecpar->codec_id != AV_CODEC_ID_AMV) {
> +        av_log(s, AV_LOG_ERROR, "First AMV stream must be %s\n",
> +                avcodec_get_name(AV_CODEC_ID_AMV));
> +        return AVERROR(EINVAL);
> +    }
> +
> +    if (ast->codecpar->codec_id != AV_CODEC_ID_ADPCM_IMA_AMV) {
> +        av_log(s, AV_LOG_ERROR, "Second AMV stream must be %s\n",
> +                avcodec_get_name(AV_CODEC_ID_ADPCM_IMA_AMV));
> +        return AVERROR(EINVAL);
> +    }
> +
> +    /* These files are broken-enough as they are. They shouldn't be streamed. */
> +    if (!(s->pb->seekable & AVIO_SEEKABLE_NORMAL)) {
> +        av_log(s, AV_LOG_ERROR, "Stream not seekable, unable to write output file\n");
> +        return AVERROR(EINVAL);
> +    }
> +
> +    amv->us_per_frame = av_rescale(AV_TIME_BASE, vst->time_base.num, vst->time_base.den);
> +    amv->aframe_size  = av_rescale(ast->codecpar->sample_rate, amv->us_per_frame, AV_TIME_BASE);
> +    amv->ablock_align = 8 + (FFALIGN(amv->aframe_size, 2) / 2);
> +
> +    av_log(s, AV_LOG_TRACE, "us_per_frame = %d\n", amv->us_per_frame);
> +    av_log(s, AV_LOG_TRACE, "aframe_size  = %d\n", amv->aframe_size);
> +    av_log(s, AV_LOG_TRACE, "ablock_align = %d\n", amv->ablock_align);
> +
> +    /*
> +     * Bail if the framerate's too high. Prevents the audio frame size from
> +     * getting too small. 63fps is the closest value to 60fps that divides
> +     * cleanly, so cap it there.
> +     */
> +    if (amv->us_per_frame < 15873) {
> +        av_log(s, AV_LOG_ERROR, "Refusing to mux >63fps video\n");
> +        return AVERROR(EINVAL);
> +    }
> +
> +    /*
> +     * frame_size will be set if coming from the encoder.
> +     * Make sure the its been configured correctly. The audio frame duration
> +     * needs to match that of the video.
> +     */
> +    if (ast->codecpar->frame_size) {
> +        AVCodecParameters *par = ast->codecpar;
> +        int bad = 0;
> +
> +        if (par->frame_size != amv->aframe_size) {
> +            av_log(s, AV_LOG_ERROR, "Invalid audio frame size. Got %d, wanted %d\n",
> +                   par->frame_size, amv->aframe_size);
> +            bad = 1;
> +        }
> +
> +        if (par->block_align != amv->ablock_align) {
> +            av_log(s, AV_LOG_ERROR, "Invalid audio block align. Got %d, wanted %d\n",
> +                   par->block_align, amv->ablock_align);
> +            bad = 1;
> +        }
> +
> +        if (bad) {
> +            av_log(s, AV_LOG_ERROR, "Try -block_size %d\n", amv->aframe_size);
> +            return AVERROR(EINVAL);
> +        }
> +
> +        if (ast->codecpar->sample_rate % amv->aframe_size) {
> +            av_log(s, AV_LOG_ERROR, "Audio sample rate not a multiple of the frame size.\n"
> +                "Please change video frame rate. Suggested rates: 10,14,15,18,21,25,30\n");
> +            return AVERROR(EINVAL);
> +        }
> +    } else {
> +        /* If remuxing from the same source, then this will match the video. */
> +        int32_t aus = av_rescale(AV_TIME_BASE, ast->time_base.num, ast->time_base.den);
> +        if (aus != amv->us_per_frame) {
> +            av_log(s, AV_LOG_ERROR, "Cannot remux streams with a different time base\n");
> +            return AVERROR(EINVAL);
> +        }
> +    }
> +
> +    /* Allocate and fill dummy packet so we can pad the audio. */
> +    if ((ret = av_new_packet(&amv->apad, amv->ablock_align)) < 0)
> +        return ret;
> +
> +    amv->apad.stream_index = AMV_STREAM_AUDIO;
> +    memset(amv->apad.data, 0, amv->ablock_align);
> +    AV_WL32(amv->apad.data + 4, amv->aframe_size);
> +
> +    av_init_packet(&amv->vpad);
> +    amv->vpad.stream_index = AMV_STREAM_VIDEO;
> +    amv->vpad.duration     = 1;
> +    return 0;
> +}
> +
> +static void amv_deinit(AVFormatContext *s)
> +{
> +    AMVContext *amv = s->priv_data;
> +
> +    av_packet_unref(&amv->apad);
> +    av_packet_unref(&amv->vpad);
> +}
> +
> +static void amv_write_vlist(AVFormatContext *s, AVCodecParameters *par)
> +{
> +    uint8_t buf[FFMAX(AMV_VIDEO_STRH_SIZE, AMV_VIDEO_STRF_SIZE)] = { 0 };
> +    int64_t tag_list, tag_str;
> +
> +    av_assert0(par->codec_id == AV_CODEC_ID_AMV);
> +
> +    tag_list = amv_start_tag(s->pb, "LIST");
> +    ffio_wfourcc(s->pb, "strl");
> +    tag_str = ff_start_tag(s->pb, "strh");
> +    avio_write(s->pb, buf, AMV_VIDEO_STRH_SIZE);

Use ffio_fill() here and in the two other places where you use write
zeroes; this also allows to no longer initialize the buf below.

> +    ff_end_tag(s->pb, tag_str);
> +
> +    tag_str = ff_start_tag(s->pb, "strf");
> +    avio_write(s->pb, buf, AMV_VIDEO_STRF_SIZE);
> +    ff_end_tag(s->pb, tag_str);
> +
> +    amv_end_tag(s->pb, tag_list);
> +}
> +
> +static void amv_write_alist(AVFormatContext *s, AVCodecParameters *par)
> +{
> +    uint8_t buf[FFMAX(AMV_AUDIO_STRH_SIZE, AMV_AUDIO_STRF_SIZE)] = { 0 };
> +    AVIOContext *pb = s->pb;
> +    int64_t tag_list, tag_str;
> +
> +    av_assert0(par->codec_id == AV_CODEC_ID_ADPCM_IMA_AMV);
> +
> +    tag_list = amv_start_tag(pb, "LIST");
> +    ffio_wfourcc(pb, "strl");
> +    tag_str = ff_start_tag(pb, "strh");
> +    avio_write(pb, buf, AMV_AUDIO_STRH_SIZE);
> +    ff_end_tag(pb, tag_str);
> +
> +    /* Bodge an (incorrect) WAVEFORMATEX (+2 pad bytes) */
> +    tag_str = ff_start_tag(pb, "strf");
> +    AV_WL16(buf +  0, 1);
> +    AV_WL16(buf +  2, par->channels);
> +    AV_WL32(buf +  4, par->sample_rate);
> +    AV_WL32(buf +  8, par->sample_rate * par->channels * 2);
> +    AV_WL16(buf + 12, 2);
> +    AV_WL16(buf + 14, 16);
> +    AV_WL16(buf + 16, 0);
> +    AV_WL16(buf + 18, 0);
> +    avio_write(pb, buf, AMV_AUDIO_STRF_SIZE);
> +    ff_end_tag(pb, tag_str);
> +
> +    amv_end_tag(pb, tag_list);
> +}
> +
> +static int amv_write_header(AVFormatContext *s)
> +{
> +    AMVContext *amv = s->priv_data;
> +    AVIOContext *pb = s->pb;
> +    AVStream *vst   = s->streams[AMV_STREAM_VIDEO];
> +    AVStream *ast   = s->streams[AMV_STREAM_AUDIO];
> +    uint8_t amvh[56] = {0};
> +    int64_t list1;
> +
> +    amv->riff_start = amv_start_tag(pb, "RIFF");
> +    ffio_wfourcc(pb, "AMV ");
> +    list1 = amv_start_tag(pb, "LIST");
> +    ffio_wfourcc(pb, "hdrl");
> +
> +    ffio_wfourcc(pb, "amvh");
> +    avio_wl32(pb, 56);
> +
> +    AV_WL32(amvh +  0, amv->us_per_frame);
> +    AV_WL32(amvh + 32, vst->codecpar->width);
> +    AV_WL32(amvh + 36, vst->codecpar->height);
> +    AV_WL32(amvh + 40, vst->time_base.den);
> +    AV_WL32(amvh + 44, vst->time_base.num);
> +    AV_WL32(amvh + 48, 0);
> +    AV_WL32(amvh + 52, 0); /* duration, filled in later. */
> +
> +    avio_write(pb, amvh, sizeof(amvh));
> +    amv->offset_duration = avio_tell(pb) - 4;
> +
> +    amv_write_vlist(s, vst->codecpar);
> +    amv_write_alist(s, ast->codecpar);
> +    amv_end_tag(pb, list1);
> +
> +    amv->movi_list = amv_start_tag(pb, "LIST");
> +    ffio_wfourcc(pb, "movi");
> +    return 0;
> +}
> +
> +static int amv_write_packet_internal(AVFormatContext *s, AVPacket *pkt)
> +{
> +    AMVContext *amv = s->priv_data;
> +
> +    if (pkt->stream_index == AMV_STREAM_VIDEO)
> +        ffio_wfourcc(s->pb, "00dc");
> +    else if (pkt->stream_index == AMV_STREAM_AUDIO)
> +        ffio_wfourcc(s->pb, "01wb");
> +    else
> +        av_assert0(0);
> +
> +    if (pkt->stream_index == AMV_STREAM_AUDIO && pkt->size != amv->ablock_align) {
> +        /* Can happen when remuxing files produced by another encoder. */
> +        av_log(s, AV_LOG_WARNING, "Invalid audio packet size (%d != %d)\n",
> +               pkt->size, amv->ablock_align);
> +    }
> +
> +    avio_wl32(s->pb, pkt->size);
> +    avio_write(s->pb, pkt->data, pkt->size);
> +
> +    amv->lastpts[pkt->stream_index] += pkt->duration;
> +    amv->last_stream = pkt->stream_index;
> +    return 0;
> +}
> +
> +static int amv_pad(AVFormatContext *s, AVPacket *pkt)
> +{
> +    AMVContext *amv = s->priv_data;
> +    int stream_index = pkt->stream_index;
> +
> +    if (stream_index != amv->last_stream)
> +        return 0;
> +
> +    stream_index = (stream_index + 1) % s->nb_streams;
> +    if (stream_index == AMV_STREAM_VIDEO)
> +        return amv_write_packet_internal(s, &amv->vpad);
> +    else if (stream_index == AMV_STREAM_AUDIO)
> +        return amv_write_packet_internal(s, &amv->apad);
> +    else
> +        av_assert0(0);
> +
> +    return AVERROR(EINVAL);
> +}
> +
> +static int amv_write_packet(AVFormatContext *s, AVPacket *pkt)
> +{
> +    AMVContext *amv = s->priv_data;
> +    int ret;
> +
> +    /* Add a dummy frame if we've received two of the same index. */
> +    if ((ret = amv_pad(s, pkt)) < 0)
> +        return ret;
> +
> +    if ((ret = amv_write_packet_internal(s, pkt)) < 0)
> +        return ret;
> +
> +    if (pkt->stream_index == AMV_STREAM_VIDEO) {
> +        /* Save the last packet for padding. */
> +        av_packet_unref(&amv->vpad);
> +        if ((ret = av_packet_ref(&amv->vpad, pkt)) < 0)
> +            return ret;
> +    }
> +
> +    return 0;
> +}
> +
> +static int amv_write_trailer(AVFormatContext *s)
> +{
> +    AMVContext *amv = s->priv_data;
> +    AVStream   *vst = s->streams[AMV_STREAM_VIDEO];
> +    AVStream   *ast = s->streams[AMV_STREAM_AUDIO];
> +    int64_t maxpts, ret;
> +    int hh, mm, ss;
> +
> +    /* Pad-out one last audio frame if needed. */
> +    if (amv->last_stream == AMV_STREAM_VIDEO) {
> +        if ((ret = amv_write_packet_internal(s, &amv->apad)) < 0)
> +            return ret;
> +    }
> +
> +    amv_end_tag(s->pb, amv->movi_list);
> +    amv_end_tag(s->pb, amv->riff_start);
> +
> +    ffio_wfourcc(s->pb, "AMV_");
> +    ffio_wfourcc(s->pb, "END_");
> +
> +    if ((ret = avio_seek(s->pb, amv->offset_duration, SEEK_SET)) < 0)
> +        return ret;
> +
> +    /* Go back and write the duration. */
> +    maxpts = FFMAX(
> +        av_rescale_q(amv->lastpts[AMV_STREAM_VIDEO], vst->time_base, AV_TIME_BASE_Q),
> +        av_rescale_q(amv->lastpts[AMV_STREAM_AUDIO], ast->time_base, AV_TIME_BASE_Q)
> +    );
> +
> +    ss  = maxpts / AV_TIME_BASE;
> +    mm  = ss / 60;
> +    hh  = mm / 60;
> +    ss %= 60;
> +    mm %= 60;
> +
> +    avio_w8(s->pb, ss);
> +    avio_w8(s->pb, mm);
> +    avio_wl16(s->pb, hh);
> +    return 0;
> +}
> +
> +AVOutputFormat ff_amv_muxer = {
> +    .name           = "amv",
> +    .long_name      = NULL_IF_CONFIG_SMALL("AMV"),
> +    .mime_type      = "video/amv",
> +    .extensions     = "amv",
> +    .priv_data_size = sizeof(AMVContext),
> +    .audio_codec    = AV_CODEC_ID_ADPCM_IMA_AMV,
> +    .video_codec    = AV_CODEC_ID_AMV,
> +    .init           = amv_init,
> +    .deinit         = amv_deinit,
> +    .write_header   = amv_write_header,
> +    .write_packet   = amv_write_packet,
> +    .write_trailer  = amv_write_trailer,
> +};
>

On 3/11/20 10:44 am, Andreas Rheinhardt wrote:
>> +static void amv_write_vlist(AVFormatContext *s, AVCodecParameters *par)
>> +{
>> +    uint8_t buf[FFMAX(AMV_VIDEO_STRH_SIZE, AMV_VIDEO_STRF_SIZE)] = { 0 };
>> +    int64_t tag_list, tag_str;
>> +
>> +    av_assert0(par->codec_id == AV_CODEC_ID_AMV);
>> +
>> +    tag_list = amv_start_tag(s->pb, "LIST");
>> +    ffio_wfourcc(s->pb, "strl");
>> +    tag_str = ff_start_tag(s->pb, "strh");
>> +    avio_write(s->pb, buf, AMV_VIDEO_STRH_SIZE);
> 
> Use ffio_fill() here and in the two other places where you use write
> zeroes; this also allows to no longer initialize the buf below.
> 

Ah, I was wondering if something like that existed. Didn't consider the 
ffio_ prefix. Reckon I should just get rid of all the buffers and change 
everything to avio_wlXX?

Zane van Iperen:
> 
> 
> On 3/11/20 10:44 am, Andreas Rheinhardt wrote:
>>> +static void amv_write_vlist(AVFormatContext *s, AVCodecParameters *par)
>>> +{
>>> +    uint8_t buf[FFMAX(AMV_VIDEO_STRH_SIZE, AMV_VIDEO_STRF_SIZE)] = { 0 };
>>> +    int64_t tag_list, tag_str;
>>> +
>>> +    av_assert0(par->codec_id == AV_CODEC_ID_AMV);
>>> +
>>> +    tag_list = amv_start_tag(s->pb, "LIST");
>>> +    ffio_wfourcc(s->pb, "strl");
>>> +    tag_str = ff_start_tag(s->pb, "strh");
>>> +    avio_write(s->pb, buf, AMV_VIDEO_STRH_SIZE);
>>
>> Use ffio_fill() here and in the two other places where you use write
>> zeroes; this also allows to no longer initialize the buf below.
>>
> 
> Ah, I was wondering if something like that existed. Didn't consider the 
> ffio_ prefix. Reckon I should just get rid of all the buffers and change 
> everything to avio_wlXX?
> 
Using a temporary buffer might be better because it avoids function call
overhead.

- Andreas