[FFmpeg-devel] [PATCH v2] ffmpeg: Add option to force a specific decode format
Fu, Linjie
linjie.fu at intel.com
Fri Nov 16 10:36:56 EET 2018
> -----Original Message-----
> From: ffmpeg-devel [mailto:ffmpeg-devel-bounces at ffmpeg.org] On Behalf
> Of Mark Thompson
> Sent: Thursday, November 15, 2018 05:48
> To: ffmpeg-devel at ffmpeg.org
> Subject: Re: [FFmpeg-devel] [PATCH v2] ffmpeg: Add option to force a
> specific decode format
>
> On 14/11/18 01:35, Fu, Linjie wrote:
> >> -----Original Message-----
> >> From: ffmpeg-devel [mailto:ffmpeg-devel-bounces at ffmpeg.org] On
> Behalf
> >> Of Mark Thompson
> >> Sent: Wednesday, November 14, 2018 09:11
> >> To: ffmpeg-devel at ffmpeg.org
> >> Subject: Re: [FFmpeg-devel] [PATCH v2] ffmpeg: Add option to force a
> >> specific decode format
> >>
> >> On 14/11/18 00:50, Fu, Linjie wrote:
> >>>> -----Original Message-----
> >>>> From: ffmpeg-devel [mailto:ffmpeg-devel-bounces at ffmpeg.org] On
> >> Behalf
> >>>> Of Mark Thompson
> >>>> Sent: Wednesday, November 14, 2018 07:44
> >>>> To: ffmpeg-devel at ffmpeg.org
> >>>> Subject: [FFmpeg-devel] [PATCH v2] ffmpeg: Add option to force a
> >> specific
> >>>> decode format
> >>>>
> >>>> Fixes #7519.
> >>>> ---
> >>>> doc/ffmpeg.texi | 13 ++++++++++++
> >>>> fftools/ffmpeg.c | 10 ++++++++++
> >>>> fftools/ffmpeg.h | 4 ++++
> >>>> fftools/ffmpeg_opt.c | 47
> >>>> ++++++++++++++++++++++++++++++++++++++++++++
> >>>> 4 files changed, 74 insertions(+)
> >>>>
> >>>> diff --git a/doc/ffmpeg.texi b/doc/ffmpeg.texi
> >>>> index 3717f22d42..d127bc0f0d 100644
> >>>> --- a/doc/ffmpeg.texi
> >>>> +++ b/doc/ffmpeg.texi
> >>>> @@ -920,6 +920,19 @@ would be more efficient.
> >>>> When doing stream copy, copy also non-key frames found at the
> >>>> beginning.
> >>>>
> >>>> + at item -decode_format[:@var{stream_specifier}]
> >>>> @var{pixfmt}[, at var{pixfmt}...] (@emph{input,per-stream})
> >>>> +Set the possible output formats to be used by the decoder for this
> >> stream.
> >>>> +If the decoder does not natively support any format in the given list
> for
> >>>> +the input stream then decoding will fail rather than continuing with a
> >>>> +different format.
> >>>> +
> >>>> +In general this should not be set - the decoder will select an output
> >>>> +format based on the input stream parameters and available
> components,
> >>>> and
> >>>> +that will be automatically converted to whatever the output requires.
> It
> >>>> +may be useful to force a hardware decoder supporting output in
> >> multiple
> >>>> +different memory types to pick a desired one, or to ensure that a
> >> hardware
> >>>> +decoder is used when software fallback is also available.
> >>>> +
> >>>> @item -init_hw_device
> >>>> @var{type}[=@var{name}][:@var{device}[, at var{key=value}...]]
> >>>> Initialise a new hardware device of type @var{type} called
> @var{name},
> >>>> using the
> >>>> given device parameters.
> >>>> diff --git a/fftools/ffmpeg.c b/fftools/ffmpeg.c
> >>>> index 38c21e944a..c651c8d3a8 100644
> >>>> --- a/fftools/ffmpeg.c
> >>>> +++ b/fftools/ffmpeg.c
> >>>> @@ -598,6 +598,7 @@ static void ffmpeg_cleanup(int ret)
> >>>> avsubtitle_free(&ist->prev_sub.subtitle);
> >>>> av_frame_free(&ist->sub2video.frame);
> >>>> av_freep(&ist->filters);
> >>>> + av_freep(&ist->decode_formats);
> >>>> av_freep(&ist->hwaccel_device);
> >>>> av_freep(&ist->dts_buffer);
> >>>>
> >>>> @@ -2800,6 +2801,15 @@ static enum AVPixelFormat
> >>>> get_format(AVCodecContext *s, const enum AVPixelFormat
> >>>> const AVCodecHWConfig *config = NULL;
> >>>> int i;
> >>>>
> >>>> + if (ist->decode_formats) {
> >>>> + for (i = 0; ist->decode_formats[i] != AV_PIX_FMT_NONE; i++) {
> >>>> + if (ist->decode_formats[i] == *p)
> >>>> + break;
> >>>> + }
> >>>> + if (ist->decode_formats[i] != *p)
> >>>> + continue;
> >>>> + }
> >>>> +
> >>>> if (!(desc->flags & AV_PIX_FMT_FLAG_HWACCEL))
> >>>> break;
> >>>>
> >>>> diff --git a/fftools/ffmpeg.h b/fftools/ffmpeg.h
> >>>> index eb1eaf6363..b06fd18b1c 100644
> >>>> --- a/fftools/ffmpeg.h
> >>>> +++ b/fftools/ffmpeg.h
> >>>> @@ -125,6 +125,8 @@ typedef struct OptionsContext {
> >>>> int nb_ts_scale;
> >>>> SpecifierOpt *dump_attachment;
> >>>> int nb_dump_attachment;
> >>>> + SpecifierOpt *decode_formats;
> >>>> + int nb_decode_formats;
> >>>> SpecifierOpt *hwaccels;
> >>>> int nb_hwaccels;
> >>>> SpecifierOpt *hwaccel_devices;
> >>>> @@ -334,6 +336,8 @@ typedef struct InputStream {
> >>>> int top_field_first;
> >>>> int guess_layout_max;
> >>>>
> >>>> + enum AVPixelFormat *decode_formats;
> >>>> +
> >>>> int autorotate;
> >>>>
> >>>> int fix_sub_duration;
> >>>> diff --git a/fftools/ffmpeg_opt.c b/fftools/ffmpeg_opt.c
> >>>> index d4851a2cd8..63bb05053b 100644
> >>>> --- a/fftools/ffmpeg_opt.c
> >>>> +++ b/fftools/ffmpeg_opt.c
> >>>> @@ -701,6 +701,7 @@ static void add_input_streams(OptionsContext
> *o,
> >>>> AVFormatContext *ic)
> >>>> AVStream *st = ic->streams[i];
> >>>> AVCodecParameters *par = st->codecpar;
> >>>> InputStream *ist = av_mallocz(sizeof(*ist));
> >>>> + char *decode_formats = NULL;
> >>>> char *framerate = NULL, *hwaccel_device = NULL;
> >>>> const char *hwaccel = NULL;
> >>>> char *hwaccel_output_format = NULL;
> >>>> @@ -797,6 +798,49 @@ static void add_input_streams(OptionsContext
> >> *o,
> >>>> AVFormatContext *ic)
> >>>> ist->top_field_first = -1;
> >>>> MATCH_PER_STREAM_OPT(top_field_first, i, ist->top_field_first,
> ic,
> >>>> st);
> >>>>
> >>>> + MATCH_PER_STREAM_OPT(decode_formats, str,
> >> decode_formats, ic,
> >>>> st);
> >>>> + if (decode_formats) {
> >>>> + const char *p, *q;
> >>>> + int i, nb_formats;
> >>>> + char tmp[32];
> >>>> +
> >>>> + nb_formats = 0;
> >>>> + for (p = decode_formats; p; p = strchr(p + 1, ','))
> >>>> + ++nb_formats;
> >>>> +
> >>>> + ist->decode_formats =
> >>>> + av_malloc_array(nb_formats + 1, sizeof(*ist-
> >>> decode_formats));
> >>>> + if (!ist->decode_formats)
> >>>> + exit_program(1);
> >>>> +
> >>>> + p = decode_formats;
> >>>> + for (i = 0; i < nb_formats; i++) {
> >>>> + q = strchr(p, ',');
> >>>> + if (!q) {
> >>>> + ist->decode_formats[i] = av_get_pix_fmt(p);
> >>>> + if (ist->decode_formats[i] == AV_PIX_FMT_NONE)
> >>>> + break;
> >>>> + continue;
> >>>> + }
> >>>> + if (q - p > sizeof(tmp) - 1)
> >>>> + break;
> >>>> + memcpy(tmp, p, q - p);
> >>>> + tmp[q - p] = 0;
> >>>> + ist->decode_formats[i] = av_get_pix_fmt(tmp);
> >>>> + if (ist->decode_formats[i] == AV_PIX_FMT_NONE)
> >>>> + break;
> >>>> + p = q + 1;
> >>>> + }
> >>>> + if (i < nb_formats) {
> >>>> + av_log(NULL, AV_LOG_FATAL,
> >>>> + "Unrecognised decode format: %s.\n", p);
> >>>> + exit_program(1);
> >>>> + }
> >>>> + ist->decode_formats[nb_formats] = AV_PIX_FMT_NONE;
> >>>> + } else {
> >>>> + ist->decode_formats = NULL;
> >>>> + }
> >>>> +
> >>>> MATCH_PER_STREAM_OPT(hwaccels, str, hwaccel, ic, st);
> >>>> if (hwaccel) {
> >>>> // The NVDEC hwaccels use a CUDA device, so remap the
> name
> >> here.
> >>>> @@ -3583,6 +3627,9 @@ const OptionDef options[] = {
> >>>> "audio bitrate (please use -b:a)", "bitrate" },
> >>>> { "b", OPT_VIDEO | HAS_ARG | OPT_PERFILE | OPT_OUTPUT,
> >>>> { .func_arg = opt_bitrate },
> >>>> "video bitrate (please use -b:v)", "bitrate" },
> >>>> + { "decode_format", OPT_VIDEO | OPT_STRING | HAS_ARG |
> >>>> OPT_EXPERT |
> >>>> + OPT_SPEC | OPT_INPUT, { .off =
> >>>> OFFSET(decode_formats) },
> >>>> + "set output format(s) to be used by decoder, fail if none of these
> >>>> formats are available", "format" },
> >>>> { "hwaccel", OPT_VIDEO | OPT_STRING | HAS_ARG |
> OPT_EXPERT
> >> |
> >>>> OPT_SPEC | OPT_INPUT, { .off =
> >>>> OFFSET(hwaccels) },
> >>>> "use HW accelerated decoding", "hwaccel name" },
> >>>> --
> >>>> 2.19.1
> >>>>
> >>>
> >>> Is there any other conditions which will cause the hwaccel failed and
> >> fallback to software path?
> >>> Like profile was not supported by hardware?
> >>
> >> If this option is set then get_format will never choose a format not on the
> list
> >> you provide, so it shouldn't be able to use software decode unless a
> >> software format is on the list.
> >>
> >>> I applied the patch and tested some cases, like yuv422 VAAPI decoding
> >> (currently not supported), HEVC decoding with unsupported profile.
> >>> It reports an error like "hwaccel initialization returned error", and
> continue
> >> to decode and produce less frames than expected. (which I thought
> fallback
> >> still happened).
> >>
> >> Can you give an example? With -v debug there will be output saying
> exactly
> >> what happened in ff_get_format().
> >>
> >> - Mark
> >
> >
> > Got information like this:
> >
> > [hevc @ 0x55b87457dbc0] Unknown HEVC profile: 0
> > [hevc @ 0x55b87457dbc0] Decoding SPS
> > [hevc @ 0x55b87457dbc0] Unknown HEVC profile: 0
> > [hevc @ 0x55b87457dbc0] Decoding PPS
> > [hevc @ 0x55b87457dbc0] Format vaapi_vld chosen by get_format().
> > [hevc @ 0x55b87457dbc0] Format vaapi_vld requires hwaccel initialisation.
> > [hevc @ 0x55b87457dbc0] Codec hevc profile 0 not supported for hardware
> decode.
> > [hevc @ 0x55b87457dbc0] Failed setup for format vaapi_vld: hwaccel
> initialisation returned error.
> > [hevc @ 0x55b87457dbc0] Format vaapi_vld not usable, retrying
> get_format() without it.
> > [hevc @ 0x55b87457dbc0] Error parsing NAL unit #3.
> > cur_dts is invalid (this is harmless if it occurs once at the start per stream)
> > [hevc @ 0x55b87458b7c0] nal_unit_type: 1(TRAIL_R), nuh_layer_id: 0,
> temporal_id: 0
> > [hevc @ 0x55b87458b7c0] Could not find ref with POC 0
> >
> > See the attached report file for more details.
>
> This is a decoder bug - get_format() is not correctly called again after it fails,
> and the decoder then uses the software pixfmt derived from the SPS on
> subsequent frames.
>
> (I did pretty much all of my testing with H.264, which does not have this
> problem.)
>
Works for me on forcing hwaccel in HEVC vaapi decoding after applying the hevcdec patch.
Thanks for answering my questions.
- Linjie
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