[FFmpeg-devel] [PATCH] avcodec: add ATRAC Advanced Lossless decoders

[Michael Niedermayer]

On Tue, Jan 31, 2017 at 04:17:19PM +0100, Paul B Mahol wrote:
> On 1/31/17, Michael Niedermayer <michaelni at gmx.at> wrote:
> > On Sun, Jan 29, 2017 at 06:39:21PM +0100, Paul B Mahol wrote:
> >> Only lossy part is decoded for now.
> >>
> >> Signed-off-by: Paul B Mahol <onemda at gmail.com>
> >> ---
> > [...]
> >>  static int oma_read_packet(AVFormatContext *s, AVPacket *pkt)
> >>  {
> >>      OMAContext *oc  = s->priv_data;
> >> -    AVStream *st    = s->streams[0];
> >> -    int packet_size = st->codecpar->block_align;
> >> -    int byte_rate   = st->codecpar->bit_rate >> 3;
> >> -    int64_t pos     = avio_tell(s->pb);
> >> -    int ret         = av_get_packet(s->pb, pkt, packet_size);
> >> -
> >> -    if (ret < packet_size)
> >> -        pkt->flags |= AV_PKT_FLAG_CORRUPT;
> >> -
> >> -    if (ret < 0)
> >> -        return ret;
> >> -    if (!ret)
> >> -        return AVERROR_EOF;
> >> -
> >> -    pkt->stream_index = 0;
> >> -
> >> -    if (pos >= oc->content_start && byte_rate > 0) {
> >> -        pkt->pts =
> >> -        pkt->dts = av_rescale(pos - oc->content_start,
> >> st->time_base.den,
> >> -                              byte_rate * (int64_t)st->time_base.num);
> >> -    }
> >> -
> >> -    if (oc->encrypted) {
> >> -        /* previous unencrypted block saved in IV for
> >> -         * the next packet (CBC mode) */
> >> -        if (ret == packet_size)
> >> -            av_des_crypt(oc->av_des, pkt->data, pkt->data,
> >> -                         (packet_size >> 3), oc->iv, 1);
> >> -        else
> >> -            memset(oc->iv, 0, 8);
> >> -    }
> >> -
> >> -    return ret;
> >> +    return oc->read_packet(s, pkt);
> >>  }
> >
> > moving this into read_packet() could be done in a seperate patch
> >
> >
> >>
> >>  static int oma_read_probe(AVProbeData *p)
> >> @@ -491,8 +571,14 @@ static int oma_read_seek(struct AVFormatContext *s,
> >>                           int stream_index, int64_t timestamp, int flags)
> >>  {
> >>      OMAContext *oc = s->priv_data;
> >> -    int64_t err = ff_pcm_read_seek(s, stream_index, timestamp, flags);
> >> +    AVStream *st = s->streams[0];
> >> +    int64_t err;
> >> +
> >> +    if (st->codecpar->codec_id == AV_CODEC_ID_ATRAC3PAL ||
> >> +        st->codecpar->codec_id == AV_CODEC_ID_ATRAC3AL)
> >
> >> +        return -1;
> >
> > should be a AVERROR code
> 
> This is not error, it makes seeking possible, using other error codes
> is bad idea.

It would be better to use a named identifier than a litteral number
normally we use AVERROR_*, i would argue that oma_read_seek() did not
seek so it didnt succeed but if you prefer this to be called something
else than AVERROR_* sure iam perfectly fine with what you prefer.

It was the use of a litteral number (which is also undocumented for
read_seek() except by code returning -1) that i wanted to comment on

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

I am the wisest man alive, for I know one thing, and that is that I know
nothing. -- Socrates
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