On Saturday, June 18, 2011 21:13:26 Christian Gmeiner wrote: > HI Hans, > > looks good... is there any progress? None. But the DECODER_CMD part would be easy enough. Before I start doing any work on this, can you match this proposed functionality to your hardware and 1) see if it fits, and 2) see if anything is missing that you need. If I know that, then I can make the necessary adjustments and try and implement this (or really, document it as that's the hardest part) perhaps by the end of this month. Regards, Hans > > -- > Christian Gmeiner, MSc > > > > 2011/6/9 Hans Verkuil <hansverk@xxxxxxxxx>: > > RFC: Proposal for a V4L2 decoder API > > ------------------------------------ > > > > This RFC is based on this discussion: > > > > http://www.mail-archive.com/linux-media@xxxxxxxxxxxxxxx/msg32703.html > > > > The purpose is to remove the dependency of ivtv to the ioctls in dvb/audio.h > > and dvb/video.h. > > > > The summary of the posting referred to above is: > > > > - Add two controls to select the audio output channels. > > - Add two read-only controls for the PTS and frame count. > > - Copy and paste the old VIDEO_(TRY_)COMMAND to VIDIOC_(TRY_)DECODER_CMD. > > > > So, here is the RFC that does that. I'm going through the items from the > > summary in reverse order. > > > > > > 1) Add new VIDIOC_TRY_DECODER_CMD and VIDIOC_DECODER_CMD ioctls. > > > > These are the decoder counterparts of the VIDIOC_(TRY_)ENCODER_CMD ioctls > > that are already in V4L2. > > > > /* Decoder commands */ > > #define V4L2_DEC_CMD_PLAY (0) > > #define V4L2_DEC_CMD_STOP (1) > > #define V4L2_DEC_CMD_FREEZE (2) > > #define V4L2_DEC_CMD_CONTINUE (3) > > > > /* Flags for V4L2_DEC_CMD_FREEZE */ > > #define V4L2_DEC_CMD_FREEZE_TO_BLACK (1 << 0) > > > > /* Flags for V4L2_DEC_CMD_STOP */ > > #define V4L2_DEC_CMD_STOP_TO_BLACK (1 << 0) > > #define V4L2_DEC_CMD_STOP_IMMEDIATELY (1 << 1) > > > > /* Play format requirements (returned by the driver): */ > > /* The decoder has no special format requirements */ > > #define V4L2_DEC_PLAY_FMT_NONE (0) > > /* The decoder requires full GOPs */ > > #define V4L2_DEC_PLAY_FMT_GOP (1) > > > > /* The structure must be zeroed before use by the application > > This ensures it can be extended safely in the future. */ > > struct v4l2_decoder_cmd { > > __u32 cmd; > > __u32 flags; > > union { > > struct { > > /* Stop when this PTS is reached */ > > __u64 pts; > > } stop; > > > > struct { > > /* 0 or 1000 specifies normal speed, > > 1 specifies forward single stepping, > > -1 specifies backward single stepping, > > >1: playback at speed/1000 of the normal speed, > > <-1: reverse playback at (-speed/1000) of the normal speed. > > */ > > __s32 speed; > > __u32 format; > > } play; > > > > struct { > > __u32 data[16]; > > } raw; > > }; > > }; > > > > Other than renaming the #defines and struct there are no changes compared to > > the current video.h API. I see no reason to change this either. > > > > > > 2) Add read-only controls for the PTS and framecount. > > > > V4L2_CID_MPEG_STREAM_DEC_PTS - integer64 > > > > Return the PTS (Presentation Time Stamp) of the currently presented frame. > > > > V4L2_CID_MPEG_VIDEO_DEC_FRAME - integer > > > > Return the frame number of the currently presented frame. When the decoder > > starts the frame counter is reset to 0. > > > > > > 3) Add two new audio selection controls. > > > > V4L2_CID_MPEG_AUDIO_DEC_CHANNEL - menu > > > > Select how to playback stereo audio from a normal audio stream: > > > > 0 - Auto (playback native format) > > 1 - Left (left channel only) > > 2 - Right (right channel only) > > 3 - Stereo > > 4 - Swapped Stereo (I'm not sure whether this should be added. Is this ever > > useful?) > > > > This control relates to its encoder counterpart V4L2_CID_MPEG_AUDIO_MODE for > > the non-DUAL modes. > > > > V4L2_CID_MPEG_AUDIO_DEC_MULTILINGUAL_CHANNEL - menu > > > > Select how to playback audio from a multilingual audio stream: > > > > 0 - Auto (either always Left or can be based on some preferred language) > > 1 - Left (left channel only) > > 2 - Right (right channel only) > > 3 - Stereo > > 4 - Swapped Stereo (I'm not sure whether this should be added. Is this ever > > useful?) > > > > This control relates to its encoder counterpart V4L2_CID_MPEG_AUDIO_MODE for > > the DUAL mode. > > > > Note that these two controls are specific to the audio layer I/II/III audio > > mode setting. They do not support any e.g. AAC decoding. More research will > > need to be done to know whether that makes sense or not. > > > > Regards, > > > > Hans > > -- > > To unsubscribe from this list: send the line "unsubscribe linux-media" in > > the body of a message to majordomo@xxxxxxxxxxxxxxx > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-media" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > > -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
