[FFmpeg-devel] [PATCH 3/4] avformat/mpegenc - accept PCM_DVD streams

[Michael Niedermayer]

On Thu, Feb 01, 2018 at 07:52:55PM +0530, Gyan Doshi wrote:
> On 1/29/2018 6:53 PM, Gyan Doshi wrote:
> >
> >On 1/29/2018 3:47 PM, Carl Eugen Hoyos wrote:
> >
> >>How did you test this patch?
> >
> >By remuxing with patched ffmpeg and then checking with ffprobe, but not
> >ffplay!
> ...
> >Sorry, I'll rework and submit.
> 
> Revised and tested patch attached.

>  mpegenc.c |   17 +++++++++++++++--
>  1 file changed, 15 insertions(+), 2 deletions(-)
> 21908814c802dffad710828d1e5ec27168586636  v2-0001-avformat-mpegenc-accept-PCM_DVD-streams.patch
> From 78757309bbfbc9d9e48aabd6babc9529f83d5950 Mon Sep 17 00:00:00 2001
> From: Gyan Doshi <gyandoshi at gmail.com>
> Date: Thu, 1 Feb 2018 19:12:03 +0530
> Subject: [PATCH v2] avformat/mpegenc - accept PCM_DVD streams
> 
> PCM_S16BE stream packets in MPEG-PS have a 3-byte header
> and recognized as PCM_DVD by the demuxer which prevents
> their proper remuxing in MPEG-1/2 PS.
> ---
>  libavformat/mpegenc.c | 17 +++++++++++++++--
>  1 file changed, 15 insertions(+), 2 deletions(-)
> 
> diff --git a/libavformat/mpegenc.c b/libavformat/mpegenc.c
> index c77c3dfe41..598df662f4 100644
> --- a/libavformat/mpegenc.c
> +++ b/libavformat/mpegenc.c
> @@ -353,7 +353,8 @@ static av_cold int mpeg_mux_init(AVFormatContext *ctx)
>              if (!s->is_mpeg2 &&
>                  (st->codecpar->codec_id == AV_CODEC_ID_AC3 ||
>                   st->codecpar->codec_id == AV_CODEC_ID_DTS ||
> -                 st->codecpar->codec_id == AV_CODEC_ID_PCM_S16BE))
> +                 st->codecpar->codec_id == AV_CODEC_ID_PCM_S16BE ||
> +                 st->codecpar->codec_id == AV_CODEC_ID_PCM_DVD))
>                   av_log(ctx, AV_LOG_WARNING,
>                          "%s in MPEG-1 system streams is not widely supported, "
>                          "consider using the vob or the dvd muxer "
> @@ -363,7 +364,10 @@ static av_cold int mpeg_mux_init(AVFormatContext *ctx)
>                  stream->id = ac3_id++;
>              } else if (st->codecpar->codec_id == AV_CODEC_ID_DTS) {
>                  stream->id = dts_id++;
> -            } else if (st->codecpar->codec_id == AV_CODEC_ID_PCM_S16BE) {
> +            } else if (st->codecpar->codec_id == AV_CODEC_ID_PCM_S16BE ||
> +                       st->codecpar->codec_id == AV_CODEC_ID_PCM_DVD) {
> +                if (st->codecpar->codec_id == AV_CODEC_ID_PCM_DVD)
> +                    av_log(ctx, AV_LOG_WARNING, "Only 16-bit LPCM streams are supported.\n");
>                  stream->id = lpcm_id++;
>                  for (j = 0; j < 4; j++) {
>                      if (lpcm_freq_tab[j] == st->codecpar->sample_rate)
> @@ -1150,8 +1154,17 @@ static int mpeg_mux_write_packet(AVFormatContext *ctx, AVPacket *pkt)
>          return AVERROR(ENOMEM);
>      pkt_desc->pts            = pts;
>      pkt_desc->dts            = dts;
> +
> +    if (st->codecpar->codec_id == AV_CODEC_ID_PCM_DVD) {
> +        /* Skip first 3 bytes of packet data, which comprise PCM header
> +           and will be written fresh by this muxer. */
> +        buf += 3;
> +        size -= 3;

Can this be reached with size < 3 ?
if so it would probably do something bad


> +    }
> +
>      pkt_desc->unwritten_size =
>      pkt_desc->size           = size;
> +
>      if (!stream->predecode_packet)
>          stream->predecode_packet = pkt_desc;
>      stream->next_packet = &pkt_desc->next;
> -- 
> 2.11.1.windows.1
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-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Its not that you shouldnt use gotos but rather that you should write
readable code and code with gotos often but not always is less readable
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