[FFmpeg-devel,1/1] Add Sega FILM muxer

From: Misty De Meo <mistydemeo@gmail.com>

---
 Changelog                 |   1 +
 libavformat/Makefile      |   1 +
 libavformat/allformats.c  |   1 +
 libavformat/segafilmenc.c | 380 ++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 383 insertions(+)
 create mode 100644 libavformat/segafilmenc.c

On 3/22/18, misty@brew.sh <misty@brew.sh> wrote:
> From: Misty De Meo <mistydemeo@gmail.com>
>
> ---
>  Changelog                 |   1 +
>  libavformat/Makefile      |   1 +
>  libavformat/allformats.c  |   1 +
>  libavformat/segafilmenc.c | 380
> ++++++++++++++++++++++++++++++++++++++++++++++
>  4 files changed, 383 insertions(+)
>  create mode 100644 libavformat/segafilmenc.c
>
> diff --git a/Changelog b/Changelog
> index 30a8978db4..0ff62ff69d 100644
> --- a/Changelog
> +++ b/Changelog
> @@ -48,6 +48,7 @@ version <next>:
>  - drmeter audio filter
>  - hapqa_extract bitstream filter
>  - filter_units bitstream filter
> +- segafilm muxer
>
>
>  version 3.4:
> diff --git a/libavformat/Makefile b/libavformat/Makefile
> index 39ec68c28b..4abb992b14 100644
> --- a/libavformat/Makefile
> +++ b/libavformat/Makefile
> @@ -462,6 +462,7 @@ OBJS-$(CONFIG_SDR2_DEMUXER)              += sdr2.o
>  OBJS-$(CONFIG_SDS_DEMUXER)               += sdsdec.o
>  OBJS-$(CONFIG_SDX_DEMUXER)               += sdxdec.o
>  OBJS-$(CONFIG_SEGAFILM_DEMUXER)          += segafilm.o
> +OBJS-$(CONFIG_SEGAFILM_MUXER)            += segafilmenc.o
>  OBJS-$(CONFIG_SEGMENT_MUXER)             += segment.o
>  OBJS-$(CONFIG_SHORTEN_DEMUXER)           += shortendec.o rawdec.o
>  OBJS-$(CONFIG_SIFF_DEMUXER)              += siff.o
> diff --git a/libavformat/allformats.c b/libavformat/allformats.c
> index 9dc5ce8a76..dfd964f07a 100644
> --- a/libavformat/allformats.c
> +++ b/libavformat/allformats.c
> @@ -364,6 +364,7 @@ extern AVInputFormat  ff_sdr2_demuxer;
>  extern AVInputFormat  ff_sds_demuxer;
>  extern AVInputFormat  ff_sdx_demuxer;
>  extern AVInputFormat  ff_segafilm_demuxer;
> +extern AVOutputFormat ff_segafilm_muxer;
>  extern AVOutputFormat ff_segment_muxer;
>  extern AVOutputFormat ff_stream_segment_muxer;
>  extern AVInputFormat  ff_shorten_demuxer;
> diff --git a/libavformat/segafilmenc.c b/libavformat/segafilmenc.c
> new file mode 100644
> index 0000000000..cc0e21d4d3
> --- /dev/null
> +++ b/libavformat/segafilmenc.c
> @@ -0,0 +1,380 @@
> +/*
> + * Cinepak Video Decoder
> + * Copyright (C) 2003 The FFmpeg project
> + *
> + * 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
> + */
> +
> +/**
> + * @file
> + * Sega FILM (.cpk) file muxer
> + * @author Misty De Meo <misty@brew.sh>
> + *
> + * @see For more information regarding the Sega FILM file format, visit:
> + *   http://wiki.multimedia.cx/index.php?title=Sega_FILM
> + */
> +
> +#include "libavutil/intreadwrite.h"
> +#include "avformat.h"
> +#include "internal.h"
> +#include "avio_internal.h"
> +
> +typedef struct FILMPacket {
> +    int audio;
> +    int keyframe;
> +    int32_t pts;
> +    int32_t duration;
> +    int32_t size;
> +    int32_t index;
> +    struct FILMPacket *next;
> +} FILMPacket;
> +
> +typedef struct FILMOutputContext {
> +    const AVClass *class;
> +    int audio_index;
> +    int video_index;
> +    int64_t stab_pos;
> +    FILMPacket *start;
> +    FILMPacket *last;
> +    int64_t packet_count;
> +} FILMOutputContext;
> +
> +static int film_write_packet_to_header(AVFormatContext *format_context,
> FILMPacket *pkt)
> +{
> +    AVIOContext *pb = format_context->pb;
> +    // The bits in these two 32-bit integers contain info about the
> contents of this sample
> +    int32_t info1 = 0;
> +    int32_t info2 = 0;
> +
> +    if (pkt->audio) {
> +        // Always the same, carries no more information than "this is
> audio"
> +        info1 = 0xFFFFFFFF;
> +        info2 = 1;
> +    } else {
> +        info1 = pkt->pts;
> +        info2 = pkt->duration;
> +        // The top bit being set indicates a key frame
> +        if (pkt->keyframe)
> +            info1 |= (1 << 31);
> +    }
> +
> +    // Write the 16-byte sample info packet to the STAB chunk in the header
> +    avio_wb32(pb, pkt->index);
> +    avio_wb32(pb, pkt->size);
> +    avio_wb32(pb, info1);
> +    avio_wb32(pb, info2);
> +
> +    return 0;
> +}
> +
> +static int film_write_packet(AVFormatContext *format_context, AVPacket
> *pkt)
> +{
> +    FILMPacket *metadata = av_mallocz(sizeof(FILMPacket));
> +    if (!metadata)
> +        return AVERROR(ENOMEM);

Do not mix initializations and calling other functions. Here and in
others places.

> +    AVIOContext *pb = format_context->pb;
> +    FILMOutputContext *film = format_context->priv_data;
> +    int encoded_buf_size = 0;
> +
> +    // Track the metadata used to write the header and add it to the linked
> list
> +    metadata->audio = pkt->stream_index == film->audio_index;
> +    metadata->keyframe = pkt->flags & AV_PKT_FLAG_KEY;
> +    metadata->pts = pkt->pts;
> +    metadata->duration = pkt->duration;
> +    metadata->size = pkt->size;
> +    if (film->last == NULL) {
> +        metadata->index = 0;
> +    } else {
> +        metadata->index = film->last->index + film->last->size;
> +        film->last->next = metadata;
> +    }
> +    metadata->next = NULL;
> +    if (film->start == NULL)
> +        film->start = metadata;
> +    film->packet_count++;
> +    film->last = metadata;
> +
> +    /* Sega Cinepak has an extra two-byte header; write dummy data there,
> +     * then adjust the cvid header to accommodate for the extra size */
> +    if (!metadata->audio) {
> +        encoded_buf_size = AV_RB24(&pkt->data[1]);
> +        // Already Sega Cinepak, so no need to reformat the packets
> +        if (encoded_buf_size != pkt->size && (pkt->size % encoded_buf_size)
> != 0) {
> +            avio_write(pb, pkt->data, pkt->size);
> +        } else {
> +            /* In Sega Cinepak, the reported size in the Cinepak header is
> +             * 8 bytes too short. However, the size in the STAB section of
> the header
> +             * is correct, taking into account the extra two bytes. */
> +            AV_WB24(&pkt->data[1], pkt->size - 8 + 2);
> +            metadata->size += 2;
> +            uint8_t padding[2] = {0, 0};
> +
> +            avio_write(pb, pkt->data, 10);
> +            avio_write(pb, padding, 2);
> +            avio_write(pb, &pkt->data[10], pkt->size - 10);
> +        }
> +    } else {
> +        // Audio can just be written as-is
> +        avio_write(pb, pkt->data, pkt->size);
> +    }
> +
> +    return 0;
> +}
> +
> +static int get_audio_codec_id(enum AVCodecID codec_id)
> +{
> +    // 0 (PCM) and 2 (ADX) are the only known values
> +    switch (codec_id) {
> +    case AV_CODEC_ID_PCM_S8:
> +    case AV_CODEC_ID_PCM_S8_PLANAR:
> +    case AV_CODEC_ID_PCM_S16BE_PLANAR:
> +        return 0;
> +        break;
> +    case AV_CODEC_ID_ADPCM_ADX:
> +        return 2;
> +        break;
> +    default:
> +        return -1;
> +    }
> +}
> +
> +static int film_init(AVFormatContext *format_context)
> +{
> +    FILMOutputContext *film = format_context->priv_data;
> +    film->audio_index = -1;
> +    film->video_index = -1;
> +    film->stab_pos = 0;
> +    film->packet_count = 0;
> +    film->start = NULL;
> +    film->last = NULL;
> +
> +    AVStream *audio = NULL;
> +
> +    for (int i = 0; i < format_context->nb_streams; i++) {
> +        AVStream *st = format_context->streams[i];
> +        if (st->codecpar->codec_type == AVMEDIA_TYPE_AUDIO) {
> +            if (film->audio_index > -1) {
> +                av_log(format_context, AV_LOG_ERROR, "Sega FILM allows a
> maximum of one audio stream.\n");
> +                return AVERROR(EINVAL);
> +            }
> +            film->audio_index = i;
> +            audio = st;
> +        }
> +
> +        if (st->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) {
> +            if (film->video_index > -1) {
> +                av_log(format_context, AV_LOG_ERROR, "Sega FILM allows a
> maximum of one video stream.\n");
> +                return AVERROR(EINVAL);
> +            }
> +            film->video_index = i;
> +        }
> +
> +        if (film->video_index == -1) {
> +            av_log(format_context, AV_LOG_ERROR, "No video stream
> present.\n");
> +            return AVERROR(EINVAL);
> +        }
> +    }
> +
> +    if (audio != NULL && get_audio_codec_id(audio->codecpar->codec_id) < 0)
> {
> +        av_log(format_context, AV_LOG_ERROR, "Incompatible audio stream
> format.\n");
> +        return AVERROR(EINVAL);
> +    }
> +
> +    return 0;
> +}
> +
> +static int shift_data(AVFormatContext *format_context, int64_t shift_size)
> +{
> +    int ret = 0;
> +    int64_t pos, pos_end = avio_tell(format_context->pb);
> +    uint8_t *buf, *read_buf[2];
> +    int read_buf_id = 0;
> +    int read_size[2];
> +    AVIOContext *read_pb;
> +
> +    buf = av_malloc(shift_size * 2);
> +    if (!buf)
> +        return AVERROR(ENOMEM);
> +    read_buf[0] = buf;
> +    read_buf[1] = buf + shift_size;
> +
> +    /* Write the header at the beginning of the file, shifting all content
> as necessary;
> +     * based on the approach used by MOV faststart. */
> +    avio_flush(format_context->pb);
> +    ret = format_context->io_open(format_context, &read_pb,
> format_context->url, AVIO_FLAG_READ, NULL);
> +    if (ret < 0) {
> +        av_log(format_context, AV_LOG_ERROR, "Unable to re-open %s output
> file to "
> +               "write the header\n", format_context->url);
> +        av_free(buf);
> +        return ret;
> +    }
> +
> +    /* mark the end of the shift to up to the last data we wrote, and get
> ready
> +     * for writing */
> +    pos_end = avio_tell(format_context->pb);
> +    avio_seek(format_context->pb, shift_size, SEEK_SET);
> +
> +    /* start reading at where the new header will be placed */
> +    avio_seek(read_pb, 0, SEEK_SET);
> +    pos = avio_tell(read_pb);
> +
> +#define READ_BLOCK do {
>         \
> +    read_size[read_buf_id] = avio_read(read_pb, read_buf[read_buf_id],
> shift_size);  \
> +    read_buf_id ^= 1;
>         \
> +} while (0)
> +
> +    /* shift data by chunk of at most shift_size */
> +    READ_BLOCK;
> +    do {
> +        int n;
> +        READ_BLOCK;
> +        n = read_size[read_buf_id];
> +        if (n <= 0)
> +            break;
> +        avio_write(format_context->pb, read_buf[read_buf_id], n);
> +        pos += n;
> +    } while (pos < pos_end);
> +    ff_format_io_close(format_context, &read_pb);
> +
> +    av_free(buf);
> +    return 0;
> +}
> +
> +static int film_write_header(AVFormatContext *format_context)
> +{
> +    int ret = 0;
> +    int64_t stabstart_pos, sample_table_size, stabsize, headersize;
> +    int8_t audio_codec;
> +    AVIOContext *pb = format_context->pb;
> +    FILMOutputContext *film = format_context->priv_data;
> +    FILMPacket *prev, *packet;
> +    AVStream *audio = NULL;
> +    AVStream *video = NULL;
> +
> +    /* Calculate how much we need to reserve for the header;
> +     * this is the amount the rest of the data will be shifted up by. */
> +    sample_table_size = film->packet_count * 16;
> +    stabsize = 16 + sample_table_size;
> +    headersize = 16 + // FILM header base
> +                 32 + // FDSC chunk
> +                 stabsize;
> +
> +    ret = shift_data(format_context, headersize);
> +    if (ret < 0)
> +        return ret;
> +    // Seek back to the beginning to start writing the header now
> +    avio_seek(pb, 0, SEEK_SET);
> +
> +    if (film->audio_index > -1)
> +        audio = format_context->streams[film->audio_index];
> +    if (film->video_index > -1)
> +        video = format_context->streams[film->video_index];
> +
> +    if (audio != NULL) {
> +        audio_codec = get_audio_codec_id(audio->codecpar->codec_id);
> +        if (audio_codec < 0) {
> +            av_log(format_context, AV_LOG_ERROR, "Incompatible audio stream
> format.\n");
> +            return AVERROR(EINVAL);

Have you checked that all audio codecs supported her do actually work?

> +        }
> +    }
> +
> +    // First, write the FILM header; this is very simple
> +
> +    ffio_wfourcc(pb, "FILM");
> +    avio_wb32(pb, 48 + stabsize);
> +    /* This seems to be okay to hardcode, since this muxer targets 1.09
> features;
> +     * videos produced by this muxer are readable by 1.08 and lower
> players. */
> +    ffio_wfourcc(pb, "1.09");
> +    // I have no idea what this field does, might be reserved
> +    avio_wb32(pb, 0);
> +
> +    // Next write the FDSC (file description) chunk
> +    ffio_wfourcc(pb, "FDSC");
> +    avio_wb32(pb, 0x20); // Size of FDSC chunk
> +    // TODO stop hardcoding this if support for another codec is added
> +    ffio_wfourcc(pb, "cvid");
> +    avio_wb32(pb, video->codecpar->height);
> +    avio_wb32(pb, video->codecpar->width);
> +    avio_w8(pb, 24); // Bits per pixel - observed to always be 24
> +
> +    if (audio != NULL) {
> +        avio_w8(pb, audio->codecpar->channels); // Audio channels
> +        avio_w8(pb, audio->codecpar->bits_per_coded_sample); // Audio bit
> depth
> +        avio_w8(pb, audio_codec); // Compression - 0 is PCM, 2 is ADX
> +        avio_wb16(pb, audio->codecpar->sample_rate); // Audio sampling rate
> +    } else {
> +        // Set all these fields to 0 if there's no audio
> +        avio_w8(pb, 0);
> +        avio_w8(pb, 0);
> +        avio_w8(pb, 0);
> +        avio_wb16(pb, 0);
> +    }
> +
> +    // I have no idea what this pair of fields does either, might be
> reserved
> +    avio_wb32(pb, 0);
> +    avio_wb16(pb, 0);
> +
> +    // Finally, write the STAB (sample table) chunk
> +    stabstart_pos = avio_tell(pb);
> +    ffio_wfourcc(pb, "STAB");
> +    avio_wb32(pb, 16 + (film->packet_count * 16));
> +    /* Framerate base frequency. Here we're assuming that the frame rate is
> even.
> +     * In real world Sega FILM files, there are usually a couple of
> approaches:
> +     * a) framerate base frequency is the same as the framerate, and ticks
> +     *    increment by 1 every frame, or
> +     * b) framerate base frequency is a much larger number, and ticks
> +     *    increment by larger steps every frame.
> +     * The latter occurs even in cases where the frame rate is even; for
> example, in
> +     * Lunar: Silver Star Story, the base frequency is 600 and each frame,
> the ticks
> +     * are incremented by 25 for an evenly spaced framerate of 24fps. */
> +    avio_wb32(pb, av_q2d(av_inv_q(video->time_base)));
> +
> +    avio_wb32(pb, film->packet_count);
> +
> +    avio_flush(pb);
> +
> +    // Finally, write out each packet's data to the header
> +    packet = film->start;
> +    while (packet != NULL)
> +    {

Put '{' above.

> +        film_write_packet_to_header(format_context, packet);
> +        prev = packet;
> +        packet = packet->next;
> +        av_freep(&prev);
> +    }
> +
> +    return 0;
> +}
> +
> +static const AVClass film_muxer_class = {
> +    .class_name     = "Sega FILM muxer",
> +    .item_name      = av_default_item_name,
> +    .version        = LIBAVUTIL_VERSION_INT,
> +};
> +
> +AVOutputFormat ff_segafilm_muxer = {
> +    .name           = "film_cpk",
> +    .long_name      = NULL_IF_CONFIG_SMALL("Sega FILM / CPK"),
> +    .extensions     = "cpk",
> +    .priv_data_size = sizeof(FILMOutputContext),
> +    .audio_codec    = AV_CODEC_ID_PCM_S16BE_PLANAR,
> +    .video_codec    = AV_CODEC_ID_CINEPAK,
> +    .init           = film_init,
> +    .write_trailer  = film_write_header,
> +    .write_packet   = film_write_packet,
> +    .priv_class     = &film_muxer_class,
> +};
> --
> 2.16.2

Generally looks pretty good.

On Wed, Mar 21, 2018 at 10:46:31PM -0700, misty@brew.sh wrote:
> From: Misty De Meo <mistydemeo@gmail.com>
[...]

> +static int film_write_header(AVFormatContext *format_context)
> +{
> +    int ret = 0;
> +    int64_t stabstart_pos, sample_table_size, stabsize, headersize;
> +    int8_t audio_codec;
> +    AVIOContext *pb = format_context->pb;
> +    FILMOutputContext *film = format_context->priv_data;
> +    FILMPacket *prev, *packet;
> +    AVStream *audio = NULL;
> +    AVStream *video = NULL;
> +
> +    /* Calculate how much we need to reserve for the header;
> +     * this is the amount the rest of the data will be shifted up by. */
> +    sample_table_size = film->packet_count * 16;
> +    stabsize = 16 + sample_table_size;
> +    headersize = 16 + // FILM header base
> +                 32 + // FDSC chunk
> +                 stabsize;
> +
> +    ret = shift_data(format_context, headersize);
> +    if (ret < 0)
> +        return ret;
> +    // Seek back to the beginning to start writing the header now
> +    avio_seek(pb, 0, SEEK_SET);
> +
> +    if (film->audio_index > -1)
> +        audio = format_context->streams[film->audio_index];
> +    if (film->video_index > -1)
> +        video = format_context->streams[film->video_index];
> +
> +    if (audio != NULL) {
> +        audio_codec = get_audio_codec_id(audio->codecpar->codec_id);
> +        if (audio_codec < 0) {
> +            av_log(format_context, AV_LOG_ERROR, "Incompatible audio stream format.\n");
> +            return AVERROR(EINVAL);
> +        }
> +    }
> +
> +    // First, write the FILM header; this is very simple
> +
> +    ffio_wfourcc(pb, "FILM");
> +    avio_wb32(pb, 48 + stabsize);
> +    /* This seems to be okay to hardcode, since this muxer targets 1.09 features;
> +     * videos produced by this muxer are readable by 1.08 and lower players. */
> +    ffio_wfourcc(pb, "1.09");
> +    // I have no idea what this field does, might be reserved
> +    avio_wb32(pb, 0);
> +
> +    // Next write the FDSC (file description) chunk
> +    ffio_wfourcc(pb, "FDSC");
> +    avio_wb32(pb, 0x20); // Size of FDSC chunk
> +    // TODO stop hardcoding this if support for another codec is added
> +    ffio_wfourcc(pb, "cvid");
> +    avio_wb32(pb, video->codecpar->height);
> +    avio_wb32(pb, video->codecpar->width);
> +    avio_w8(pb, 24); // Bits per pixel - observed to always be 24
> +
> +    if (audio != NULL) {
> +        avio_w8(pb, audio->codecpar->channels); // Audio channels
> +        avio_w8(pb, audio->codecpar->bits_per_coded_sample); // Audio bit depth
> +        avio_w8(pb, audio_codec); // Compression - 0 is PCM, 2 is ADX
> +        avio_wb16(pb, audio->codecpar->sample_rate); // Audio sampling rate
> +    } else {
> +        // Set all these fields to 0 if there's no audio
> +        avio_w8(pb, 0);
> +        avio_w8(pb, 0);
> +        avio_w8(pb, 0);
> +        avio_wb16(pb, 0);
> +    }
> +
> +    // I have no idea what this pair of fields does either, might be reserved
> +    avio_wb32(pb, 0);
> +    avio_wb16(pb, 0);
> +

> +    // Finally, write the STAB (sample table) chunk
> +    stabstart_pos = avio_tell(pb);

this is set but never used


[...]

From: Misty De Meo <mistydemeo@gmail.com>

> Just move allocation after all declarations.

OK, changed.

> Do you check that this condition is set in code?
>
> I mean, if user set codec for wrong case.

Oh, good point. I thought about this, and then realized that for mono audio,
there is no difference between planar and non-planar. If the muxer only accepts
planar then it'll work in both cases and there doesn't have to be a special
check. That also matches the behaviour of the demuxer, which marks streams as
planar regardless of channel layout.

> this is set but never used

Good catch - removed. Left over from an older version of the header generation.

Misty De Meo (1):
  Add Sega FILM muxer

 Changelog                 |   1 +
 libavformat/Makefile      |   1 +
 libavformat/allformats.c  |   1 +
 libavformat/segafilmenc.c | 377 ++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 380 insertions(+)
 create mode 100644 libavformat/segafilmenc.c