[FFmpeg-devel] [PATCH 1/5] lavc/qsvenc: add forced_idr opiton

[Mark Thompson]

On 29/10/18 21:29, Rogozhkin, Dmitry V wrote:
> On Mon, 2018-10-29 at 21:06 +0000, Mark Thompson wrote:
>> On 25/10/18 13:36, Zhong Li wrote:
>>> This option can be used to repect original input I/IDR frame type.
>>>
>>> Signed-off-by: Zhong Li <zhong.li at intel.com>
>>> ---
>>>  libavcodec/qsvenc.c | 7 +++++++
>>>  libavcodec/qsvenc.h | 2 ++
>>>  2 files changed, 9 insertions(+)
>>>
>>> diff --git a/libavcodec/qsvenc.c b/libavcodec/qsvenc.c
>>> index 948751d..e534dcf 100644
>>> --- a/libavcodec/qsvenc.c
>>> +++ b/libavcodec/qsvenc.c
>>> @@ -1192,6 +1192,13 @@ static int encode_frame(AVCodecContext
>>> *avctx, QSVEncContext *q,
>>>      if (qsv_frame) {
>>>          surf = &qsv_frame->surface;
>>>          enc_ctrl = &qsv_frame->enc_ctrl;
>>> +
>>> +        if (q->forced_idr >= 0 && frame->pict_type ==
>>> AV_PICTURE_TYPE_I) {
>>> +            enc_ctrl->FrameType = MFX_FRAMETYPE_I |
>>> MFX_FRAMETYPE_REF;
>>> +            if (q->forced_idr || frame->key_frame)
>>> +                enc_ctrl->FrameType |= MFX_FRAMETYPE_IDR;
>>> +        } else
>>> +            enc_ctrl->FrameType = MFX_FRAMETYPE_UNKNOWN;
>>>      }
>>>  
>>>      ret = av_new_packet(&new_pkt, q->packet_size);
>>> diff --git a/libavcodec/qsvenc.h b/libavcodec/qsvenc.h
>>> index 055b4a6..1f97f77 100644
>>> --- a/libavcodec/qsvenc.h
>>> +++ b/libavcodec/qsvenc.h
>>> @@ -87,6 +87,7 @@
>>>  { "adaptive_i",     "Adaptive I-frame
>>> placement",             OFFSET(qsv.adaptive_i),     AV_OPT_TYPE_INT
>>> , { .i64 = -1 }, -1,          1, VE },                         \
>>>  { "adaptive_b",     "Adaptive B-frame
>>> placement",             OFFSET(qsv.adaptive_b),     AV_OPT_TYPE_INT
>>> , { .i64 = -1 }, -1,          1, VE },                         \
>>>  { "b_strategy",     "Strategy to choose between I/P/B-frames",
>>> OFFSET(qsv.b_strategy),    AV_OPT_TYPE_INT, { .i64 = -1 },
>>> -1,          1, VE },                         \
>>> +{ "forced_idr",     "Forcing I frames as IDR
>>> frames",         OFFSET(qsv.forced_idr),     AV_OPT_TYPE_INT, {
>>> .i64 = -1 }, -1,          1, VE },                         \
>>>  
>>>  typedef int SetEncodeCtrlCB (AVCodecContext *avctx,
>>>                               const AVFrame *frame, mfxEncodeCtrl*
>>> enc_ctrl);
>>> @@ -168,6 +169,7 @@ typedef struct QSVEncContext {
>>>  #endif
>>>      char *load_plugins;
>>>      SetEncodeCtrlCB *set_encode_ctrl_cb;
>>> +    int forced_idr;
>>>  } QSVEncContext;
>>>  
>>>  int ff_qsv_enc_init(AVCodecContext *avctx, QSVEncContext *q);
>>>
>>
>> This seems confusing, because it doesn't match what forced_idr does
>> in any other encoder.
>>
>> Checking of pict_type for AV_PICTURE_TYPE_I in order to get a key
>> frame (of whatever kind) is always enabled if supported (many
>> encoders).  The "forced_idr" option to H.26[45] encoders (libx264,
>> libx265) then forces that to be an IDR frame, not just an I frame.
> 
> Is there an option to disable/override this behavior? Will "-
> force_key_frames" do the trick?

Not in libavcodec; encoders always looks at pict_type (e.g. <http://git.videolan.org/?p=ffmpeg.git;a=blob;f=libavcodec/libx264.c;h=d6367bf557953ec4e91d057d551848b3b2ba9d36;hb=HEAD#l300>).

"-force_key_frames" is an option to the ffmpeg utility which sets pict_type dependent on some expression, making use of the above behaviour.

- Mark