[FFmpeg-devel] [PATCH 3/4] lavc: Add wrapped_avframe decoder

[Mark Thompson]

On 03/09/17 18:25, Muhammad Faiz wrote:
> On Sun, Sep 3, 2017 at 5:21 AM, Mark Thompson <sw at jkqxz.net> wrote:
>> Intended for use with hardware frames for which rawvideo is not
>> sufficient.
>> ---
>> Kindof nasty.  Any thoughts on better ways of achieving the same result (hardware frames out of lavd) very welcome!
>>
>>
>>  libavcodec/Makefile          |  1 +
>>  libavcodec/allcodecs.c       |  2 +-
>>  libavcodec/wrapped_avframe.c | 31 +++++++++++++++++++++++++++++++
>>  3 files changed, 33 insertions(+), 1 deletion(-)
>>
>> diff --git a/libavcodec/Makefile b/libavcodec/Makefile
>> index 999632cf9e..943e5db511 100644
>> --- a/libavcodec/Makefile
>> +++ b/libavcodec/Makefile
>> @@ -653,6 +653,7 @@ OBJS-$(CONFIG_WMV2_DECODER)            += wmv2dec.o wmv2.o wmv2data.o \
>>  OBJS-$(CONFIG_WMV2_ENCODER)            += wmv2enc.o wmv2.o wmv2data.o \
>>                                            msmpeg4.o msmpeg4enc.o msmpeg4data.o
>>  OBJS-$(CONFIG_WNV1_DECODER)            += wnv1.o
>> +OBJS-$(CONFIG_WRAPPED_AVFRAME_DECODER) += wrapped_avframe.o
>>  OBJS-$(CONFIG_WRAPPED_AVFRAME_ENCODER) += wrapped_avframe.o
>>  OBJS-$(CONFIG_WS_SND1_DECODER)         += ws-snd1.o
>>  OBJS-$(CONFIG_XAN_DPCM_DECODER)        += dpcm.o
>> diff --git a/libavcodec/allcodecs.c b/libavcodec/allcodecs.c
>> index ce0bc7ecf3..625720578f 100644
>> --- a/libavcodec/allcodecs.c
>> +++ b/libavcodec/allcodecs.c
>> @@ -377,7 +377,7 @@ static void register_all(void)
>>      REGISTER_DECODER(VQA,               vqa);
>>      REGISTER_DECODER(BITPACKED,         bitpacked);
>>      REGISTER_DECODER(WEBP,              webp);
>> -    REGISTER_ENCODER(WRAPPED_AVFRAME,   wrapped_avframe);
>> +    REGISTER_ENCDEC (WRAPPED_AVFRAME,   wrapped_avframe);
>>      REGISTER_ENCDEC (WMV1,              wmv1);
>>      REGISTER_ENCDEC (WMV2,              wmv2);
>>      REGISTER_DECODER(WMV3,              wmv3);
>> diff --git a/libavcodec/wrapped_avframe.c b/libavcodec/wrapped_avframe.c
>> index 14360320ff..e66f0cfa4c 100644
>> --- a/libavcodec/wrapped_avframe.c
>> +++ b/libavcodec/wrapped_avframe.c
>> @@ -75,6 +75,28 @@ static int wrapped_avframe_encode(AVCodecContext *avctx, AVPacket *pkt,
>>      return 0;
>>  }
>>
>> +static int wrapped_avframe_decode(AVCodecContext *avctx, void *data,
>> +                                  int *got_frame, AVPacket *pkt)
>> +{
>> +    AVFrame *in, *out;
>> +    int err;
>> +
>> +    if (pkt->size < sizeof(AVFrame))
>> +        return AVERROR(EINVAL);
>> +
>> +    in  = (AVFrame*)pkt->data;
>> +    out = data;
>> +
>> +    err = ff_decode_frame_props(avctx, out);
>> +    if (err < 0)
>> +        return err;
>> +
>> +    av_frame_move_ref(out, in);
>> +
>> +    *got_frame = 1;
>> +    return 0;
>> +}
>> +
>>  AVCodec ff_wrapped_avframe_encoder = {
>>      .name           = "wrapped_avframe",
>>      .long_name      = NULL_IF_CONFIG_SMALL("AVFrame to AVPacket passthrough"),
>> @@ -83,3 +105,12 @@ AVCodec ff_wrapped_avframe_encoder = {
>>      .encode2        = wrapped_avframe_encode,
>>      .caps_internal  = FF_CODEC_CAP_INIT_THREADSAFE,
>>  };
>> +
>> +AVCodec ff_wrapped_avframe_decoder = {
>> +    .name           = "wrapped_avframe",
>> +    .long_name      = NULL_IF_CONFIG_SMALL("AVPacket to AVFrame passthrough"),
>> +    .type           = AVMEDIA_TYPE_VIDEO,
>> +    .id             = AV_CODEC_ID_WRAPPED_AVFRAME,
>> +    .decode         = wrapped_avframe_decode,
>> +    .caps_internal  = FF_CODEC_CAP_INIT_THREADSAFE,
>> +};
>> --
>> 2.11.0
> 
> Security issues:
> https://ffmpeg.org/pipermail/ffmpeg-devel/2015-November/182985.html

Hmm, yeah, urgh.  I didn't think of this decoder being callable standalone.

Does anyone want to propose a different solution to the idea of a flag on the packet?  That seems straightforward enough.

(Or any other ideas to get the frame out of lavd.  For kmsgrab the inability to do that is entirely fatal - it needs to carry the hardware context metadata, so rawvideo just doesn't work.)

Thanks,

- Mark