On Sun, Sep 5, 2021 at 6:12 PM Andreas Rheinhardt <
andreas.rheinha...@outlook.com> wrote:
> Paul B Mahol:
> > Signed-off-by: Paul B Mahol <one...@gmail.com>
> > ---
> > libavformat/mlpdec.c | 38 +++++++++++++++++++++++++++++++++++---
> > 1 file changed, 35 insertions(+), 3 deletions(-)
> >
> > diff --git a/libavformat/mlpdec.c b/libavformat/mlpdec.c
> > index 8f0aabb510..f13d0fac8c 100644
> > --- a/libavformat/mlpdec.c
> > +++ b/libavformat/mlpdec.c
> > @@ -22,8 +22,11 @@
> > */
> >
> > #include "avformat.h"
> > +#include "avio_internal.h"
> > +#include "internal.h"
> > #include "rawdec.h"
> > #include "libavutil/intreadwrite.h"
> > +#include "libavcodec/mlp_parse.h"
> >
> > static int av_always_inline mlp_thd_probe(const AVProbeData *p,
> uint32_t sync)
> > {
> > @@ -50,6 +53,36 @@ static int av_always_inline mlp_thd_probe(const
> AVProbeData *p, uint32_t sync)
> > return 0;
> > }
> >
> > +static int mlp_read_header(AVFormatContext *s)
> > +{
> > + int ret = ff_raw_audio_read_header(s);
> > +
> > + if (ret < 0)
> > + return ret;
> > +
> > + ret = ffio_ensure_seekback(s->pb, 10);
> > + if (ret == 0) {
> > + int sample_rate, type;
> > +
> > + avio_skip(s->pb, 7);
> > + type = avio_r8(s->pb);
> > +
> > + switch (type) {
> > + case 0xba:
> > + sample_rate = mlp_samplerate(avio_r8(s->pb) >> 4);
> > + break;
> > + case 0xbb:
> > + sample_rate = mlp_samplerate((avio_rb16(s->pb) >> 4) & 0xF);
> > + break;
> > + }
> > +
> > + avpriv_set_pts_info(s->streams[0], 64, 1, sample_rate);
> > + avio_seek(s->pb, -9 - (type == 0xbb), SEEK_CUR);
>
> This presumes that one of the two cases of the switch will be taken.
> I think it would be easier if you just read the first 10 bytes into a
> stack buffer and parsed from it instead. Then you can always seek back
> by 10 bytes.
>
> (I always thought that thd can have very high samplerates (up to
> 192kHz). Am I wrong?)
>
Yes, but lowest is 44100 Hz.
>
> > + }
> > +
> > + return 0;
> > +}
> > +
> > #if CONFIG_MLP_DEMUXER
> > static int mlp_probe(const AVProbeData *p)
> > {
> > @@ -60,7 +93,7 @@ const AVInputFormat ff_mlp_demuxer = {
> > .name = "mlp",
> > .long_name = NULL_IF_CONFIG_SMALL("raw MLP"),
> > .read_probe = mlp_probe,
> > - .read_header = ff_raw_audio_read_header,
> > + .read_header = mlp_read_header,
> > .read_packet = ff_raw_read_partial_packet,
> > .flags = AVFMT_GENERIC_INDEX | AVFMT_NOTIMESTAMPS,
> > .extensions = "mlp",
> > @@ -80,7 +113,7 @@ const AVInputFormat ff_truehd_demuxer = {
> > .name = "truehd",
> > .long_name = NULL_IF_CONFIG_SMALL("raw TrueHD"),
> > .read_probe = thd_probe,
> > - .read_header = ff_raw_audio_read_header,
> > + .read_header = mlp_read_header,
> > .read_packet = ff_raw_read_partial_packet,
> > .flags = AVFMT_GENERIC_INDEX | AVFMT_NOTIMESTAMPS,
> > .extensions = "thd",
> > @@ -89,4 +122,3 @@ const AVInputFormat ff_truehd_demuxer = {
> > .priv_class = &ff_raw_demuxer_class,
> > };
> > #endif
> > -
> >
>
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