[FFmpeg-devel] [PATCH] avformat: add TiVo ty demuxer

[Michael Niedermayer]

On Wed, Nov 01, 2017 at 02:40:27PM +0100, Paul B Mahol wrote:
> Signed-off-by: Paul B Mahol <onemda at gmail.com>
> ---
>  libavformat/Makefile     |   1 +
>  libavformat/allformats.c |   1 +
>  libavformat/ty.c         | 775 +++++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 777 insertions(+)
>  create mode 100644 libavformat/ty.c

[...]

> +static int64_t get_pts(const uint8_t *buf)
> +{
> +    int a = buf[0] & 0xe >> 1;
> +    int b = AV_RB16(buf + 1);
> +    int c = AV_RB16(buf + 3);
> +
> +    if (!(1 & a & b & c))
> +        return AV_NOPTS_VALUE;
> +
> +    a >>= 1;
> +    b >>= 1;
> +    c >>= 1;
> +    return (((uint64_t)a) << 30) | (b << 15) | c;
> +}

duplicate of ff_parse_pes_pts()

i didnt check most of the code but seeing this, i wonder how much
more mpeg demuxing this duplicates ?


> +
> +static int DemuxRecVideo(AVFormatContext *s, TyRecHdr *rec_hdr, AVPacket *pkt)
> +{
> +    TYDemuxContext *ty = s->priv_data;
> +    AVIOContext *pb = s->pb;
> +    const int subrec_type = rec_hdr->subrec_type;
> +    const int64_t rec_size = rec_hdr->rec_size;
> +    int esOffset1;
> +    int got_packet = 0;
> +
> +    avio_read(pb, ty->chunk, 32);
> +    avio_seek(pb, -32, SEEK_CUR);
> +
> +    if (subrec_type != 0x02 && subrec_type != 0x0c &&
> +        subrec_type != 0x08 && rec_size > 4) {
> +        /* get the PTS from this packet if it has one.
> +         * on S1, only 0x06 has PES.  On S2, however, most all do.
> +         * Do NOT Pass the PES Header to the MPEG2 codec */
> +        esOffset1 = find_es_header(ty_VideoPacket, ty->chunk, 5);
> +        if (esOffset1 != -1) {
> +            ty->last_video_pts = get_pts(
> +                    &ty->chunk[ esOffset1 + VIDEO_PTS_OFFSET ] );
> +            if (subrec_type != 0x06) {
> +                /* if we found a PES, and it's not type 6, then we're S2 */
> +                /* The packet will have video data (& other headers) so we
> +                 * chop out the PES header and send the rest */
> +                if (rec_size >= VIDEO_PES_LENGTH + esOffset1) {
> +                    int size = rec_hdr->rec_size - VIDEO_PES_LENGTH - esOffset1;
> +                    avio_skip(pb, VIDEO_PES_LENGTH + esOffset1);

> +                    av_get_packet(pb, pkt, size);

this and other av_get_packet() calls lack error handling

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Complexity theory is the science of finding the exact solution to an
approximation. Benchmarking OTOH is finding an approximation of the exact
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