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ffmpeg/libavformat/amvenc.c

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/*
* 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 "mux.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; not owned by us. */
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);
}
av_assert1(ast->codecpar->codec_id == AV_CODEC_ID_ADPCM_IMA_AMV);
/* 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. */
amv->apad = ffformatcontext(s)->pkt;
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);
amv->vpad = av_packet_alloc();
if (!amv->vpad) {
return AVERROR(ENOMEM);
}
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_free(&amv->vpad);
}
static void amv_write_vlist(AVFormatContext *s, AVCodecParameters *par)
{
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");
ffio_fill(s->pb, 0, AMV_VIDEO_STRH_SIZE);
ff_end_tag(s->pb, tag_str);
tag_str = ff_start_tag(s->pb, "strf");
ffio_fill(s->pb, 0, 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[AMV_AUDIO_STRF_SIZE];
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");
ffio_fill(s->pb, 0, 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->ch_layout.nb_channels);
AV_WL32(buf + 4, par->sample_rate);
AV_WL32(buf + 8, par->sample_rate * par->ch_layout.nb_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;
}
const FFOutputFormat ff_amv_muxer = {
.p.name = "amv",
.p.long_name = NULL_IF_CONFIG_SMALL("AMV"),
.p.mime_type = "video/amv",
.p.extensions = "amv",
.priv_data_size = sizeof(AMVContext),
.p.audio_codec = AV_CODEC_ID_ADPCM_IMA_AMV,
.p.video_codec = AV_CODEC_ID_AMV,
.p.subtitle_codec = AV_CODEC_ID_NONE,
.flags_internal = FF_OFMT_FLAG_MAX_ONE_OF_EACH |
FF_OFMT_FLAG_ONLY_DEFAULT_CODECS,
.init = amv_init,
.deinit = amv_deinit,
.write_header = amv_write_header,
.write_packet = amv_write_packet,
.write_trailer = amv_write_trailer,
};
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