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 <z...@zanevaniperen.com>
> ---
> MAINTAINERS | 1 +
> libavformat/Makefile | 1 +
> libavformat/allformats.c | 1 +
> libavformat/amvenc.c | 408 +++++++++++++++++++++++++++++++++++++++
> 4 files changed, 411 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..5088440d28
> --- /dev/null
> +++ b/libavformat/amvenc.c
> @@ -0,0 +1,408 @@
> +/*
> + * AMV muxer
> + *
> + * Copyright (C) 2020 Zane van Iperen (z...@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)
Doesn't seem to be unreferenced anywhere.
> + 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.buf = NULL;
av_init_packet() already does this.
> + amv->vpad.size = 0;
The context has already been zeroed initially.
> + amv->vpad.duration = 1;
> + return 0;
> +}
> +
> +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);
> + 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);
> + av_packet_ref(&amv->vpad, pkt);
Missing check.
> + }
> +
> + 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_");
> +
> + av_packet_unref(&amv->vpad);
This should be done in a deinit function so that nothing leaks if
write_trailer is not called.
> +
> + 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,
> + .write_header = amv_write_header,
> + .write_packet = amv_write_packet,
> + .write_trailer = amv_write_trailer,
> +};
>
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