[FFmpeg-devel] [PATCH] avformat/flvenc: add flv live stream flag
Michael Niedermayer
michael at niedermayer.cc
Thu Sep 29 19:53:16 EEST 2016
On Thu, Sep 29, 2016 at 09:25:35PM +0800, Steven Liu wrote:
> patch update
>
> merge 1/2 and 2/2 into one patch
> doc/muxers.texi | 5 +++++
> libavformat/flvenc.c | 50 +++++++++++++++++++++++++++++---------------------
> 2 files changed, 34 insertions(+), 21 deletions(-)
> f2c4c83d362faf1819b3aa72fc5608603f824dc1 0001-avformat-flvenc-add-flv-live-stream-flag.patch
> From 7f5ff0d89c19e1683f91befb77ba4a7bf7b66252 Mon Sep 17 00:00:00 2001
> From: Steven Liu <lingjiujianke at gmail.com>
> Date: Thu, 29 Sep 2016 21:20:34 +0800
> Subject: [PATCH] avformat/flvenc: add flv live stream flag
>
> If the flv format is used for live stream on publish
> ffmpeg should not update dutration and filesize at the end.
> because the live stream is sent metadata at first step.
>
> Reviewed-by: Carl Eugen Hoyos <cehoyos at ag.or.at>
> Signed-off-by: Steven Liu <lingjiujianke at gmail.com>
> ---
> doc/muxers.texi | 5 +++++
> libavformat/flvenc.c | 50 +++++++++++++++++++++++++++++---------------------
> 2 files changed, 34 insertions(+), 21 deletions(-)
>
> diff --git a/doc/muxers.texi b/doc/muxers.texi
> index 27d1038..aa20656 100644
> --- a/doc/muxers.texi
> +++ b/doc/muxers.texi
> @@ -148,6 +148,11 @@ Place AAC sequence header based on audio stream data.
> @item no_sequence_end
> Disable sequence end tag.
> @end table
> +
> + at item live_stream
> +Disable the duration and filesize update in the flv metadata.
> + at end table
> +
> @end table
>
> @anchor{framecrc}
> diff --git a/libavformat/flvenc.c b/libavformat/flvenc.c
> index 99903f5..cd9ca84 100644
> --- a/libavformat/flvenc.c
> +++ b/libavformat/flvenc.c
> @@ -64,6 +64,7 @@ static const AVCodecTag flv_audio_codec_ids[] = {
> typedef enum {
> FLV_AAC_SEQ_HEADER_DETECT = (1 << 0),
> FLV_NO_SEQUENCE_END = (1 << 1),
> + FLV_LIVE_STREAM = (1 << 2),
> } FLVFlags;
>
> typedef struct FLVContext {
> @@ -234,17 +235,18 @@ static void write_metadata(AVFormatContext *s, unsigned int ts)
> metadata_count_pos = avio_tell(pb);
> metadata_count = 4 * !!flv->video_par +
> 5 * !!flv->audio_par +
> - 1 * !!flv->data_par +
> - 2; // +2 for duration and file size
> + 1 * !!flv->data_par;
>
> avio_wb32(pb, metadata_count);
>
> - put_amf_string(pb, "duration");
> - flv->duration_offset = avio_tell(pb);
> -
> - // fill in the guessed duration, it'll be corrected later if incorrect
> - put_amf_double(pb, s->duration / AV_TIME_BASE);
> + if (!(flv->flags & FLV_LIVE_STREAM)) {
> + put_amf_string(pb, "duration");
> + flv->duration_offset = avio_tell(pb);
>
> + // fill in the guessed duration, it'll be corrected later if incorrect
> + put_amf_double(pb, s->duration / AV_TIME_BASE);
> + metadata_count++;
> + }
> if (flv->video_par) {
> put_amf_string(pb, "width");
> put_amf_double(pb, flv->video_par->width);
> @@ -319,10 +321,12 @@ static void write_metadata(AVFormatContext *s, unsigned int ts)
> metadata_count++;
> }
>
> - put_amf_string(pb, "filesize");
> - flv->filesize_offset = avio_tell(pb);
> - put_amf_double(pb, 0); // delayed write
> -
> + if (!(flv->flags & FLV_LIVE_STREAM)) {
> + put_amf_string(pb, "filesize");
> + flv->filesize_offset = avio_tell(pb);
> + put_amf_double(pb, 0); // delayed write
> + metadata_count++
> + }
> put_amf_string(pb, "");
> avio_w8(pb, AMF_END_OF_OBJECT);
>
> @@ -543,16 +547,19 @@ static int flv_write_trailer(AVFormatContext *s)
>
> file_size = avio_tell(pb);
>
> - /* update information */
> - if (avio_seek(pb, flv->duration_offset, SEEK_SET) < 0)
> - av_log(s, AV_LOG_WARNING, "Failed to update header with correct duration.\n");
> - else
> - put_amf_double(pb, flv->duration / (double)1000);
> - if (avio_seek(pb, flv->filesize_offset, SEEK_SET) < 0)
> - av_log(s, AV_LOG_WARNING, "Failed to update header with correct filesize.\n");
> - else
> - put_amf_double(pb, file_size);
> -
> + if (!(flv->flags & FLV_LIVE_STREAM)) {
> + /* update information */
> + if (avio_seek(pb, flv->duration_offset, SEEK_SET) < 0) {
> + av_log(s, AV_LOG_WARNING, "Failed to update header with correct duration.\n");
> + } else {
> + put_amf_double(pb, flv->duration / (double)1000);
> + }
> + if (avio_seek(pb, flv->filesize_offset, SEEK_SET) < 0) {
> + av_log(s, AV_LOG_WARNING, "Failed to update header with correct filesize.\n");
> + } else {
> + put_amf_double(pb, file_size);
> + }
> + }
> avio_seek(pb, file_size, SEEK_SET);
> return 0;
> }
> @@ -729,6 +736,7 @@ static const AVOption options[] = {
> { "flvflags", "FLV muxer flags", offsetof(FLVContext, flags), AV_OPT_TYPE_FLAGS, {.i64 = 0}, INT_MIN, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM, "flvflags" },
> { "aac_seq_header_detect", "Put AAC sequence header based on stream data", 0, AV_OPT_TYPE_CONST, {.i64 = FLV_AAC_SEQ_HEADER_DETECT}, INT_MIN, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM, "flvflags" },
> { "no_sequence_end", "disable sequence end for FLV", 0, AV_OPT_TYPE_CONST, {.i64 = FLV_NO_SEQUENCE_END}, INT_MIN, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM, "flvflags" },
> + { "live_stream", "used for flv live stream mode", 0, AV_OPT_TYPE_CONST, {.i64 = FLV_LIVE_STREAM}, INT_MIN, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM, "flvflags" },
> { NULL },
i may misunderstand the intend but you can use
pb->seekable
to identify if the output protocol supports seeking
(a live stream where data was already sent could not support seeking)
OTOH
if the intend is to create files on seekable media that lack duration/
filesize then the patch should be ok
[...]
--
Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
Dictatorship naturally arises out of democracy, and the most aggravated
form of tyranny and slavery out of the most extreme liberty. -- Plato
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