[FFmpeg-devel] [PATCH 1/2] Add experimental muxing support for FLAC in ISO BMFF (MP4).
James Almer
jamrial at gmail.com
Fri Nov 18 03:57:49 EET 2016
On 11/1/2016 8:21 PM, Matthew Gregan wrote:
> At 2016-11-01T00:56:45-0300, James Almer wrote:
>> > The muxer gets the extradata as created by the encoder only during init().
>> > Even if the encoder changes it in any way afterwards, it will never make
>> > it to the muxer. That's why packet side data is used for this.
>> >
>> > The reason the encoder used the AVCodecContext extradata to store the
>> > updated Streaminfo before creating the packet side data is most likely
>> > because it was an already allocated buffer. Technically, it's not the
>> > "proper" thing to do, but it also doesn't seem to make a difference.
> Makes sense, thanks for the explanation.
>
> Updated patch attached with the following changes:
> - Uses libavcodec/flac.h for the FLAC_STREAMINFO_SIZE and
> FLAC_METADATA_TYPE_STREAMINFO definitions, per the feedback on the demuxer
> patch.
> - Fixes the sample size in bits written to the 'fLaC' audio box.
> Thanks to Vittorio Giovara for pointing this out.
>
>
> 0001-Add-experimental-muxing-support-for-FLAC-in-ISO-BMFF.patch
>
>
> From e08e1b5041a331d640d190c39c00bdc61e81243c Mon Sep 17 00:00:00 2001
> From: Matthew Gregan <kinetik at flim.org>
> Date: Thu, 20 Oct 2016 17:28:11 +1300
> Subject: [PATCH 1/2] Add experimental muxing support for FLAC in ISO BMFF
> (MP4).
>
> Based on the draft spec at https://git.xiph.org/?p=flac.git;a=blob;f=doc/isoflac.txt
>
> '-strict -2' is required to create files in this format.
>
> Signed-off-by: Matthew Gregan <kinetik at flim.org>
> ---
> libavformat/isom.c | 2 ++
> libavformat/movenc.c | 46 +++++++++++++++++++++++++++++++++++++++++++---
> 2 files changed, 45 insertions(+), 3 deletions(-)
>
> diff --git a/libavformat/isom.c b/libavformat/isom.c
> index ab79e22..aacbe43 100644
> --- a/libavformat/isom.c
> +++ b/libavformat/isom.c
> @@ -60,6 +60,7 @@ const AVCodecTag ff_mp4_obj_type[] = {
> { AV_CODEC_ID_EAC3 , 0xA6 },
> { AV_CODEC_ID_DTS , 0xA9 }, /* mp4ra.org */
> { AV_CODEC_ID_VP9 , 0xC0 }, /* nonstandard, update when there is a standard value */
> + { AV_CODEC_ID_FLAC , 0xC1 }, /* nonstandard, update when there is a standard value */
> { AV_CODEC_ID_TSCC2 , 0xD0 }, /* nonstandard, camtasia uses it */
> { AV_CODEC_ID_VORBIS , 0xDD }, /* nonstandard, gpac uses it */
> { AV_CODEC_ID_DVD_SUBTITLE, 0xE0 }, /* nonstandard, see unsupported-embedded-subs-2.mp4 */
> @@ -345,6 +346,7 @@ const AVCodecTag ff_codec_movaudio_tags[] = {
> { AV_CODEC_ID_WMAV2, MKTAG('W', 'M', 'A', '2') },
> { AV_CODEC_ID_EVRC, MKTAG('s', 'e', 'v', 'c') }, /* 3GPP2 */
> { AV_CODEC_ID_SMV, MKTAG('s', 's', 'm', 'v') }, /* 3GPP2 */
> + { AV_CODEC_ID_FLAC, MKTAG('f', 'L', 'a', 'C') }, /* nonstandard */
This is enables muxing into mov, which bypasses the experimental check below
since mov isn't MODE_MP4.
> { AV_CODEC_ID_NONE, 0 },
> };
>
> diff --git a/libavformat/movenc.c b/libavformat/movenc.c
> index 6228192..06f6dc6 100644
> --- a/libavformat/movenc.c
> +++ b/libavformat/movenc.c
> @@ -33,6 +33,7 @@
> #include "avc.h"
> #include "libavcodec/ac3_parser.h"
> #include "libavcodec/dnxhddata.h"
> +#include "libavcodec/flac.h"
> #include "libavcodec/get_bits.h"
> #include "libavcodec/put_bits.h"
> #include "libavcodec/vc1_common.h"
> @@ -654,6 +655,26 @@ static int mov_write_wfex_tag(AVFormatContext *s, AVIOContext *pb, MOVTrack *tra
> return update_size(pb, pos);
> }
>
> +static int mov_write_dfla_tag(AVIOContext *pb, MOVTrack *track)
> +{
> + int64_t pos = avio_tell(pb);
> + avio_wb32(pb, 0);
> + ffio_wfourcc(pb, "dfLa");
> + avio_w8(pb, 0); /* version */
> + avio_wb24(pb, 0); /* flags */
> +
> + /* Expect the encoder to pass a METADATA_BLOCK_TYPE_STREAMINFO. */
> + if (track->par->extradata_size != FLAC_STREAMINFO_SIZE)
> + return AVERROR_INVALIDDATA;
> +
> + /* TODO: Write other METADATA_BLOCK_TYPEs if the encoder makes them available. */
> + avio_w8(pb, 1 << 7 | FLAC_METADATA_TYPE_STREAMINFO); /* LastMetadataBlockFlag << 7 | BlockType */
> + avio_wb24(pb, track->par->extradata_size); /* Length */
> + avio_write(pb, track->par->extradata, track->par->extradata_size); /* BlockData[Length] */
> +
> + return update_size(pb, pos);
> +}
> +
> static int mov_write_chan_tag(AVFormatContext *s, AVIOContext *pb, MOVTrack *track)
> {
> uint32_t layout_tag, bitmap;
> @@ -963,8 +984,13 @@ static int mov_write_audio_tag(AVFormatContext *s, AVIOContext *pb, MOVMuxContex
> avio_wb16(pb, 16);
> avio_wb16(pb, track->audio_vbr ? -2 : 0); /* compression ID */
> } else { /* reserved for mp4/3gp */
> - avio_wb16(pb, 2);
> - avio_wb16(pb, 16);
> + if (track->par->codec_id == AV_CODEC_ID_FLAC) {
> + avio_wb16(pb, track->par->channels);
> + avio_wb16(pb, track->par->bits_per_raw_sample);
> + } else {
> + avio_wb16(pb, 2);
> + avio_wb16(pb, 16);
> + }
> avio_wb16(pb, 0);
> }
>
> @@ -1009,6 +1035,8 @@ static int mov_write_audio_tag(AVFormatContext *s, AVIOContext *pb, MOVMuxContex
> mov_write_extradata_tag(pb, track);
> else if (track->par->codec_id == AV_CODEC_ID_WMAPRO)
> mov_write_wfex_tag(s, pb, track);
> + else if (track->par->codec_id == AV_CODEC_ID_FLAC)
> + mov_write_dfla_tag(pb, track);
> else if (track->vos_len > 0)
> mov_write_glbl_tag(pb, track);
>
> @@ -1177,6 +1205,7 @@ static int mp4_get_codec_tag(AVFormatContext *s, MOVTrack *track)
> else if (track->par->codec_id == AV_CODEC_ID_DIRAC) tag = MKTAG('d','r','a','c');
> else if (track->par->codec_id == AV_CODEC_ID_MOV_TEXT) tag = MKTAG('t','x','3','g');
> else if (track->par->codec_id == AV_CODEC_ID_VC1) tag = MKTAG('v','c','-','1');
> + else if (track->par->codec_id == AV_CODEC_ID_FLAC) tag = MKTAG('f','L','a','C');
> else if (track->par->codec_type == AVMEDIA_TYPE_VIDEO) tag = MKTAG('m','p','4','v');
> else if (track->par->codec_type == AVMEDIA_TYPE_AUDIO) tag = MKTAG('m','p','4','a');
> else if (track->par->codec_id == AV_CODEC_ID_DVD_SUBTITLE) tag = MKTAG('m','p','4','s');
> @@ -5019,7 +5048,8 @@ static int mov_write_single_packet(AVFormatContext *s, AVPacket *pkt)
> trk->start_cts = 0;
> }
>
> - if (trk->par->codec_id == AV_CODEC_ID_MP4ALS) {
> + if (trk->par->codec_id == AV_CODEC_ID_MP4ALS ||
> + trk->par->codec_id == AV_CODEC_ID_FLAC) {
> int side_size = 0;
> uint8_t *side = av_packet_get_side_data(pkt, AV_PKT_DATA_NEW_EXTRADATA, &side_size);
> if (side && side_size > 0 && (side_size != par->extradata_size || memcmp(side, par->extradata, side_size))) {
> @@ -5733,6 +5763,16 @@ static int mov_init(AVFormatContext *s)
> i, track->par->sample_rate);
> }
> }
> + if (track->mode == MODE_MP4 &&
> + track->par->codec_id == AV_CODEC_ID_FLAC) {
> + if (s->strict_std_compliance > FF_COMPLIANCE_EXPERIMENTAL) {
> + av_log(s, AV_LOG_ERROR,
> + "FLAC in MP4 support is experimental, add "
> + "'-strict %d' if you want to use it.\n",
> + FF_COMPLIANCE_EXPERIMENTAL);
> + return AVERROR_EXPERIMENTAL;
> + }
> + }
> } else if (st->codecpar->codec_type == AVMEDIA_TYPE_SUBTITLE) {
> track->timescale = st->time_base.den;
> } else if (st->codecpar->codec_type == AVMEDIA_TYPE_DATA) {
> -- 2.10.1
>
>
>
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