[FFmpeg-devel] [PATCH 1/7] Revert "Revert "lavfi/buffersrc: push the frame deeper if requested.""

[Tobias Rapp]

On 17.07.2017 16:19, Nicolas George wrote:
> This reverts commit 04aa09c4bcf2d5a634a35da3a3ae3fc1abe30ef8.
> 
> The fate-ffm change is caused by field_order now being set
> on the output format because the first frame arrives earlier.
> The fate-mxf change is assumed to be the same.
> 
> Signed-off-by: Nicolas George <george at nsup.org>
> ---
>   libavfilter/buffersrc.c | 25 +++++++++++++++++++++++++
>   tests/ref/lavf/ffm      |  2 +-
>   tests/ref/lavf/mxf      |  6 +++---
>   3 files changed, 29 insertions(+), 4 deletions(-)
> 
> [...]
This commit seems to break transcoding of some input files on machines 
with a lot of CPU cores. See attached script that reproduces the problem 
("-threads 32" is used to simulate the situation of a multi-core CPU).

Sorry for noticing late but it took me some time to track down the 
problem and git bisecting it. The issue seems to be triggered by the 
high number of audio packets in the input file (~375 packets per 
second). Input files that have a lower audio packet rate work fine.

Regards,
Tobias
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#!/bin/bash

# =========================================================================
# Configuration

BASE_PATH="./debug"
INPUT_FILE="$BASE_PATH/ffmpeg-test-input.avi"
OUTPUT_FILE="$BASE_PATH/ffmpeg-test-output.avi"
TEMP_FILE="$BASE_PATH/ffmpeg-test-temp.wav"

FFMPEG_PATH="."
FFMPEG_BIN="$FFMPEG_PATH/build-linux/ffmpeg-dbg"

# =========================================================================
# Create Input Files

mkdir -p "$BASE_PATH"

$FFMPEG_BIN \
  -flags +bitexact -sws_flags +accurate_rnd+bitexact -fflags +bitexact \
  -f lavfi -graph "aevalsrc=sin(440*2*PI*t):sample_rate=48000:channel_layout=7.1" -i dummy1 \
  -f wav -codec:a pcm_f32le -t 30.0 -y "$TEMP_FILE"

$FFMPEG_BIN \
  -flags +bitexact -sws_flags +accurate_rnd+bitexact -fflags +bitexact \
  -f lavfi -graph "testsrc2=size=720x576:rate=25:sar=16/15,noise=alls=40:allf=t+u" -i dummy1 \
  -i "$TEMP_FILE" \
  -f avi -codec:v ffvhuff -pix_fmt yuv422p -codec:a pcm_s24le -t 30.0 -y "$INPUT_FILE"

# =========================================================================
# Create Output File

$FFMPEG_BIN \
  -flags +bitexact -sws_flags +accurate_rnd+bitexact -fflags +bitexact \
  -threads 32 -probesize 50M -ss 3.0 -i "$INPUT_FILE" \
  -f avi -map 0:v -map 0:a -codec:v ffvhuff -pix_fmt yuv422p \
  -codec:a pcm_s24le -loglevel repeat+verbose -xerror \
  -y "$OUTPUT_FILE"

if [ $? -eq 0 ]; then
  echo "=== TEST SUCCEEDED ===";
else
  echo "=== TEST FAILED ===";
fi