[FFmpeg-devel] [PATCH v2 1/3] avformat/mpegtsenc: Fix mpegts_write_pes() for private_stream_2 and other types

[Mao Hata]

On 2021/04/20 13:44, zheng qian wrote:
> Changes since v1:
>    Separate if-statement and cosmetic changes into different commits
> 
> According to the PES packet definition defined in Table 2-17
> of ISO_IEC_13818-1 specification, some fields like PTS/DTS or
> pes_extension could only appears if the stream_id meets the
> condition:
> 
> if (stream_id != 0xBC &&  // program_stream_map
> stream_id != 0xBE &&  // padding_stream
> stream_id != 0xBF &&  // private_stream_2
> stream_id != 0xF0 &&  // ECM
> stream_id != 0xF1 &&  // EMM
> stream_id != 0xFF &&  // program_stream_directory
> stream_id != 0xF2 &&  // DSMCC_stream
> stream_id != 0xF8)     // ITU-T Rec. H.222.1 type E stream
> 
> And the following stream_id types don't have fields like PTS/DTS:
> 
> else if ( stream_id == program_stream_map
> || stream_id == private_stream_2
> || stream_id == ECM
> || stream_id == EMM
> || stream_id == program_stream_directory
> || stream_id == DSMCC_stream
> || stream_id == ITU-T Rec. H.222.1 type E stream ) {
>      for (i = 0; i < PES_packet_length; i++) {
>          PES_packet_data_byte
>      }
> }
> 
> Current implementation skipped the judgement of stream_id
> causing some kind of stream like private_stream_2 to be
> incorrectly written with PTS/DTS field. For example,
> Japan DTV transmits news and alerts through ARIB superimpose
> that utilizes private_stream_2 still could not be remuxed
> correctly for now.
> 
> This patch set fixes the remuxing for private_stream_2 and
> other stream_id types.
> 
> Signed-off-by: zheng qian <xqq at xqq.im>
> ---
>   libavformat/mpegtsenc.c | 11 +++++++++++
>   1 file changed, 11 insertions(+)
> 
> diff --git a/libavformat/mpegtsenc.c b/libavformat/mpegtsenc.c
> index f302af84ff..0c543c385b 100644
> --- a/libavformat/mpegtsenc.c
> +++ b/libavformat/mpegtsenc.c
> @@ -1524,6 +1524,16 @@ static void mpegts_write_pes(AVFormatContext *s, AVStream *st,
>               }
>               *q++ = len >> 8;
>               *q++ = len;
> +
> +            if (stream_id != 0xBC &&  // program_stream_map
> +                stream_id != 0xBE &&  // padding_stream
> +                stream_id != 0xBF &&  // private_stream_2
> +                stream_id != 0xF0 &&  // ECM
> +                stream_id != 0xF1 &&  // EMM
> +                stream_id != 0xFF &&  // program_stream_directory
> +                stream_id != 0xF2 &&  // DSMCC_stream
> +                stream_id != 0xF8) {  // ITU-T Rec. H.222.1 type E stream
> +
>               val  = 0x80;
>               /* data alignment indicator is required for subtitle and data streams */
>               if (st->codecpar->codec_type == AVMEDIA_TYPE_SUBTITLE || st->codecpar->codec_type == AVMEDIA_TYPE_DATA)
> @@ -1569,6 +1579,7 @@ static void mpegts_write_pes(AVFormatContext *s, AVStream *st,
>                   memset(q, 0xff, pes_header_stuffing_bytes);
>                   q += pes_header_stuffing_bytes;
>               }
> +            }
>               is_start = 0;
>           }
>           /* header size */
> 

PES_packet_length seems to be inaccurate, because "header_len + 3" has 
already been added to the variable "len".