[FFmpeg-devel] [PATCH 1/2] avcodec: Implement Acorn Replay IMA ADPCM decoder

[Cameron Cawley]

Samples are available from
http://riscos.com/ftp_space/370/files/diversions.zip (in the "AudioDemos"
folder) and http://riscos.com/ftp_space/370/files/sound.zip (the files
"1812" and "Enigma").

On Fri, 5 Jul 2019 at 17:16, Michael Niedermayer <michael at niedermayer.cc>
wrote:

> On Thu, Jun 27, 2019 at 08:56:01PM +0100, Cameron Cawley wrote:
> > Signed-off-by: Cameron Cawley <ccawley2011 at gmail.com>
> > ---
> >  doc/general.texi        |  1 +
> >  libavcodec/Makefile     |  1 +
> >  libavcodec/adpcm.c      | 14 ++++++++++++++
> >  libavcodec/allcodecs.c  |  1 +
> >  libavcodec/avcodec.h    |  1 +
> >  libavcodec/codec_desc.c |  7 +++++++
> >  libavcodec/utils.c      |  1 +
> >  7 files changed, 26 insertions(+)
> >
> > diff --git a/doc/general.texi b/doc/general.texi
> > index ed3cdfcf99..fbbbc24753 100644
> > --- a/doc/general.texi
> > +++ b/doc/general.texi
> > @@ -1070,6 +1070,7 @@ following image formats are supported:
> >  @item ADPCM Electronic Arts XAS @tab     @tab  X
> >  @item ADPCM G.722            @tab  X  @tab  X
> >  @item ADPCM G.726            @tab  X  @tab  X
> > + at item ADPCM IMA Acorn Replay @tab     @tab  X
> >  @item ADPCM IMA AMV          @tab     @tab  X
> >      @tab Used in AMV files
> >  @item ADPCM IMA Electronic Arts EACS  @tab     @tab  X
> > diff --git a/libavcodec/Makefile b/libavcodec/Makefile
> > index edccd73037..9c0dd5d189 100644
> > --- a/libavcodec/Makefile
> > +++ b/libavcodec/Makefile
> > @@ -825,6 +825,7 @@ OBJS-$(CONFIG_ADPCM_G726_DECODER)         += g726.o
> >  OBJS-$(CONFIG_ADPCM_G726_ENCODER)         += g726.o
> >  OBJS-$(CONFIG_ADPCM_G726LE_DECODER)       += g726.o
> >  OBJS-$(CONFIG_ADPCM_G726LE_ENCODER)       += g726.o
> > +OBJS-$(CONFIG_ADPCM_IMA_ACORN_DECODER)    += adpcm.o adpcm_data.o
> >  OBJS-$(CONFIG_ADPCM_IMA_AMV_DECODER)      += adpcm.o adpcm_data.o
> >  OBJS-$(CONFIG_ADPCM_IMA_APC_DECODER)      += adpcm.o adpcm_data.o
> >  OBJS-$(CONFIG_ADPCM_IMA_DAT4_DECODER)     += adpcm.o adpcm_data.o
> > diff --git a/libavcodec/adpcm.c b/libavcodec/adpcm.c
> > index ede0130bf1..1d4b4d2c22 100644
> > --- a/libavcodec/adpcm.c
> > +++ b/libavcodec/adpcm.c
> > @@ -594,6 +594,7 @@ static int get_nb_samples(AVCodecContext *avctx,
> GetByteContext *gb,
> >      switch (avctx->codec->id) {
> >          case AV_CODEC_ID_ADPCM_4XM:
> >          case AV_CODEC_ID_ADPCM_AGM:
> > +        case AV_CODEC_ID_ADPCM_IMA_ACORN:
> >          case AV_CODEC_ID_ADPCM_IMA_DAT4:
> >          case AV_CODEC_ID_ADPCM_IMA_ISS:     header_size = 4 * ch;
> break;
> >          case AV_CODEC_ID_ADPCM_IMA_AMV:     header_size = 8;
>  break;
> > @@ -1412,6 +1413,18 @@ static int adpcm_decode_frame(AVCodecContext
> *avctx, void *data,
> >              }
> >          }
> >          break;
> > +    case AV_CODEC_ID_ADPCM_IMA_ACORN:
> > +        for (i=0; i<=st; i++) {
> > +            bytestream2_skip(&gb, 2); // TODO: What does this do?
> > +            c->status[i].step_index = bytestream2_get_le16u(&gb);
> > +        }
>
> where can we find such adpcm files for testing ?
>
> 2 bytes per stream could be initial raw pcm samples
>
> thx
>
> [...]
> --
> Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
>
> No great genius has ever existed without some touch of madness. --
> Aristotle
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