[FFmpeg-devel] [PATCH 2/2] avcodec/mjpegdec: add support for frame threading

[Timo Rothenpieler]

On 05.12.2022 15:15, Andreas Rheinhardt wrote:
> Timo Rothenpieler:
>> In my tests, this lead to a notable speed increase with the amount
>> of threads used. Decoding a 720p sample gave the following results:
>>
>> 1 Thread: 1428 FPS
>> 2 Threads: 2501 FPS
>> 8 Threads: 7575 FPS
>> Automatic: 11326 FPS (On a 16 Core/32 Threads system)
>> ---
>>   libavcodec/jpeglsdec.c |  2 +-
>>   libavcodec/mjpegdec.c  | 13 +++++++------
>>   libavcodec/sp5xdec.c   |  4 ++--
>>   3 files changed, 10 insertions(+), 9 deletions(-)
>>
>> diff --git a/libavcodec/jpeglsdec.c b/libavcodec/jpeglsdec.c
>> index 2e6d018ea6..c0642e8e30 100644
>> --- a/libavcodec/jpeglsdec.c
>> +++ b/libavcodec/jpeglsdec.c
>> @@ -559,7 +559,7 @@ const FFCodec ff_jpegls_decoder = {
>>       .init           = ff_mjpeg_decode_init,
>>       .close          = ff_mjpeg_decode_end,
>>       FF_CODEC_RECEIVE_FRAME_CB(ff_mjpeg_receive_frame),
>> -    .p.capabilities = AV_CODEC_CAP_DR1,
>> +    .p.capabilities = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_FRAME_THREADS,
>>       .caps_internal  = FF_CODEC_CAP_INIT_CLEANUP |
>>                         FF_CODEC_CAP_SETS_PKT_DTS,
>>   };
>> diff --git a/libavcodec/mjpegdec.c b/libavcodec/mjpegdec.c
>> index 9b7465abe7..d30d722398 100644
>> --- a/libavcodec/mjpegdec.c
>> +++ b/libavcodec/mjpegdec.c
>> @@ -54,6 +54,7 @@
>>   #include "exif.h"
>>   #include "bytestream.h"
>>   #include "tiff_common.h"
>> +#include "thread.h"
>>   
>>   
>>   static int init_default_huffman_tables(MJpegDecodeContext *s)
>> @@ -713,7 +714,7 @@ int ff_mjpeg_decode_sof(MJpegDecodeContext *s)
>>                   s->avctx->pix_fmt,
>>                   AV_PIX_FMT_NONE,
>>               };
>> -            s->hwaccel_pix_fmt = ff_get_format(s->avctx, pix_fmts);
>> +            s->hwaccel_pix_fmt = ff_thread_get_format(s->avctx, pix_fmts);
>>               if (s->hwaccel_pix_fmt < 0)
>>                   return AVERROR(EINVAL);
>>   
>> @@ -729,7 +730,7 @@ int ff_mjpeg_decode_sof(MJpegDecodeContext *s)
>>           }
>>   
>>           av_frame_unref(s->picture_ptr);
>> -        if (ff_get_buffer(s->avctx, s->picture_ptr, AV_GET_BUFFER_FLAG_REF) < 0)
>> +        if (ff_thread_get_buffer(s->avctx, s->picture_ptr, AV_GET_BUFFER_FLAG_REF) < 0)
>>               return -1;
>>           s->picture_ptr->pict_type = AV_PICTURE_TYPE_I;
>>           s->picture_ptr->key_frame = 1;
>> @@ -2388,7 +2389,7 @@ static int mjpeg_get_packet(AVCodecContext *avctx)
>>       int ret;
>>   
>>       av_packet_unref(s->pkt);
>> -    ret = ff_decode_get_packet(avctx, s->pkt);
>> +    ret = ff_thread_decode_get_packet(avctx, s->pkt);
>>       if (ret < 0)
>>           return ret;
>>   
>> @@ -3020,7 +3021,7 @@ const FFCodec ff_mjpeg_decoder = {
>>       .close          = ff_mjpeg_decode_end,
>>       FF_CODEC_RECEIVE_FRAME_CB(ff_mjpeg_receive_frame),
>>       .flush          = decode_flush,
>> -    .p.capabilities = AV_CODEC_CAP_DR1,
>> +    .p.capabilities = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_FRAME_THREADS,
>>       .p.max_lowres   = 3,
>>       .p.priv_class   = &mjpegdec_class,
>>       .p.profiles     = NULL_IF_CONFIG_SMALL(ff_mjpeg_profiles),
>> @@ -3050,7 +3051,7 @@ const FFCodec ff_thp_decoder = {
>>       .close          = ff_mjpeg_decode_end,
>>       FF_CODEC_RECEIVE_FRAME_CB(ff_mjpeg_receive_frame),
>>       .flush          = decode_flush,
>> -    .p.capabilities = AV_CODEC_CAP_DR1,
>> +    .p.capabilities = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_FRAME_THREADS,
>>       .p.max_lowres   = 3,
>>       .caps_internal  = FF_CODEC_CAP_INIT_CLEANUP |
>>                         FF_CODEC_CAP_SETS_PKT_DTS,
>> @@ -3068,7 +3069,7 @@ const FFCodec ff_smvjpeg_decoder = {
>>       .close          = ff_mjpeg_decode_end,
>>       FF_CODEC_RECEIVE_FRAME_CB(ff_mjpeg_receive_frame),
>>       .flush          = decode_flush,
>> -    .p.capabilities = AV_CODEC_CAP_DR1,
>> +    .p.capabilities = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_FRAME_THREADS,
>>       .caps_internal  = FF_CODEC_CAP_EXPORTS_CROPPING |
>>                         FF_CODEC_CAP_SETS_PKT_DTS | FF_CODEC_CAP_INIT_CLEANUP,
>>   };
>> diff --git a/libavcodec/sp5xdec.c b/libavcodec/sp5xdec.c
>> index 394448c5a9..8b08dc672a 100644
>> --- a/libavcodec/sp5xdec.c
>> +++ b/libavcodec/sp5xdec.c
>> @@ -101,7 +101,7 @@ const FFCodec ff_sp5x_decoder = {
>>       .init           = ff_mjpeg_decode_init,
>>       .close          = ff_mjpeg_decode_end,
>>       FF_CODEC_RECEIVE_FRAME_CB(ff_mjpeg_receive_frame),
>> -    .p.capabilities = AV_CODEC_CAP_DR1,
>> +    .p.capabilities = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_FRAME_THREADS,
>>       .p.max_lowres   = 3,
>>       .caps_internal  = FF_CODEC_CAP_INIT_CLEANUP |
>>                         FF_CODEC_CAP_SETS_PKT_DTS,
>> @@ -118,7 +118,7 @@ const FFCodec ff_amv_decoder = {
>>       .close          = ff_mjpeg_decode_end,
>>       FF_CODEC_RECEIVE_FRAME_CB(ff_mjpeg_receive_frame),
>>       .p.max_lowres   = 3,
>> -    .p.capabilities = AV_CODEC_CAP_DR1,
>> +    .p.capabilities = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_FRAME_THREADS,
>>       .caps_internal  = FF_CODEC_CAP_INIT_CLEANUP |
>>                         FF_CODEC_CAP_SETS_PKT_DTS,
>>   };
> 
> Can you test the sample that Michael mentioned here:
> https://patchwork.ffmpeg.org/project/ffmpeg/patch/AS8PR01MB7944E105BE990A5D01EF89208FEF9@AS8PR01MB7944.eurprd01.prod.exchangelabs.com/?
> (I never got around to analyzing this, but if I am not mistaken, it
> shows that this decoder is not a simple one-in, one-out decoder, so that
> making it multithreaded will be more complicated than just adding the
> flag and using ff_thread_get_buffer/format.)

Assuming this is the right file:
https://trac.ffmpeg.org/attachment/ticket/1915/not_interleaved.avi

It does not decode for me at all, with or without this patch applied:

> [mjpeg @ 0x562e81877c80] No JPEG data found in image
> Error while decoding stream #0:0: Invalid data found when processing input