Re: [FFmpeg-devel] [PATCH] lavc/cuvid: fail early if GPU can't handle video parameters

[Pavel Koshevoy]

On 01/12/2017 10:32 AM, Timo Rothenpieler wrote:

On 1/9/2017 7:22 PM, pkoshe...@gmail.com wrote:

From: Pavel Koshevoy <pkoshe...@gmail.com>

Evidently CUVID doesn't support decoding 422 or 444 chroma formats,
and only a limited set of resolutions per codec are supported.

Given that stream resolution and pixel format are typically known as a
result of probing it is better to use this info during avcodec_open2
call and fail early in case the video parameters are not supported,
rather than failing later during avcodec_send_packet calls.

This problem surfaced when trying to decode 5120x2700 h246 video on
GeForce GT 730, or when decoding 422 mpeg2/h264 streams on same GPU -
avcodec_open2 succeeds but decoding fails.
---
  libavcodec/cuvid.c | 62 +++++++++++++++++++++++++++++++++++++++++++++++++-----
  1 file changed, 57 insertions(+), 5 deletions(-)

diff --git a/libavcodec/cuvid.c b/libavcodec/cuvid.c
index 8fc713d..ed21f94 100644
--- a/libavcodec/cuvid.c
+++ b/libavcodec/cuvid.c
@@ -612,7 +612,11 @@ static av_cold int cuvid_decode_end(AVCodecContext *avctx)
      return 0;
  }

-static int cuvid_test_dummy_decoder(AVCodecContext *avctx, CUVIDPARSERPARAMS *cuparseinfo)

+static int cuvid_test_dummy_decoder(AVCodecContext *avctx,
+                                    const CUVIDPARSERPARAMS *cuparseinfo,
+                                    cudaVideoChromaFormat probed_chroma_format,
+                                    int probed_width,
+                                    int probed_height)
  {
      CuvidContext *ctx = avctx->priv_data;
      CUVIDDECODECREATEINFO cuinfo;
@@ -622,11 +626,11 @@ static int cuvid_test_dummy_decoder(AVCodecContext 
*avctx, CUVIDPARSERPARAMS *cu
      memset(&cuinfo, 0, sizeof(cuinfo));

cuinfo.CodecType = cuparseinfo->CodecType;

-    cuinfo.ChromaFormat = cudaVideoChromaFormat_420;
+    cuinfo.ChromaFormat = probed_chroma_format;
      cuinfo.OutputFormat = cudaVideoSurfaceFormat_NV12;

- cuinfo.ulWidth = 1280;

-    cuinfo.ulHeight = 720;
+    cuinfo.ulWidth = probed_width;
+    cuinfo.ulHeight = probed_height;
      cuinfo.ulTargetWidth = cuinfo.ulWidth;
      cuinfo.ulTargetHeight = cuinfo.ulHeight;

@@ -653,6 +657,36 @@ static int cuvid_test_dummy_decoder(AVCodecContext *avctx, CUVIDPARSERPARAMS *cu

      return 0;
  }

+static int convert_to_cuda_video_chroma_format(enum AVPixelFormat pix_fmt,

+                                               cudaVideoChromaFormat *out)
+{
+    const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(pix_fmt);
+    if (!(out && desc &&
+          (desc->nb_components == 1 || desc->nb_components == 3) &&
+          (desc->log2_chroma_w < 2 && desc->log2_chroma_h < 2)))
+    {
+        return AVERROR(EINVAL);
+    }
+
+    if (desc->nb_components == 1)
+    {
+        *out = cudaVideoChromaFormat_Monochrome;
+    }
+    else if (desc->flags == AV_PIX_FMT_FLAG_PLANAR)
+    {
+        *out = ((desc->log2_chroma_w == 0) ? cudaVideoChromaFormat_444 :
+                (desc->log2_chroma_h == 0) ? cudaVideoChromaFormat_422 :
+                cudaVideoChromaFormat_420);
+    }
+    else
+    {
+        return AVERROR(EINVAL);
+    }
+
+    // unfortunately, 420 is the only one that works:
+    return (*out == cudaVideoChromaFormat_420) ? 0 : AVERROR_EXTERNAL;
+}
+
  static av_cold int cuvid_decode_init(AVCodecContext *avctx)
  {
      CuvidContext *ctx = avctx->priv_data;
@@ -663,12 +697,27 @@ static av_cold int cuvid_decode_init(AVCodecContext 
*avctx)
      CUcontext cuda_ctx = NULL;
      CUcontext dummy;
      const AVBitStreamFilter *bsf;
+    cudaVideoChromaFormat probed_chroma_format;
+    int probed_width;
+    int probed_height;
      int ret = 0;

enum AVPixelFormat pix_fmts[3] = { AV_PIX_FMT_CUDA,

                                         AV_PIX_FMT_NV12,
                                         AV_PIX_FMT_NONE };

+ enum AVPixelFormat probed_pix_fmt = (avctx->pix_fmt < 0 ?

Shouldn't this be <= 0? If unset it will most likely be 0.
Also, the braces seem unneccesary or misplaced.

+                                         AV_PIX_FMT_YUV420P :
+                                         avctx->pix_fmt);
+
+    ret = convert_to_cuda_video_chroma_format(probed_pix_fmt, 
&probed_chroma_format);
+    if (ret < 0) {
+        // pixel format is not supported:

Printing an error here would be better, instead of failing init without
any indication what went wrong.

+        return ret;
+    }
+    probed_width = avctx->coded_width ? avctx->coded_width : 1280;
+    probed_height = avctx->coded_height ? avctx->coded_height : 720;
+
      // Accelerated transcoding scenarios with 'ffmpeg' require that the
      // pix_fmt be set to AV_PIX_FMT_CUDA early. The sw_pix_fmt, and the
      // pix_fmt for non-accelerated transcoding, do not need to be correct
@@ -824,7 +873,10 @@ static av_cold int cuvid_decode_init(AVCodecContext *avctx)
      if (ret < 0)
          goto error;

- ret = cuvid_test_dummy_decoder(avctx, &ctx->cuparseinfo);

+    ret = cuvid_test_dummy_decoder(avctx, &ctx->cuparseinfo,
+                                   probed_chroma_format,
+                                   probed_width,
+                                   probed_height);
      if (ret < 0)
          goto error;

LGTM otherwise

This patch was rejected by wm4, so consider it dropped.

    Pavel.
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