flvEncoder .flv output won't convert to .mp4 with ffmpeg [duplicate]

Question

This question already has an answer here:

FFmpeg converting image sequence to video results in blank video [closed] (1 answer)

Closed 5 years ago.

My current project involves creating a .flv using AIR (using https://github.com/zeropointnine/leelib/tree/master/src/leelib/util/flvEncoder) - which then has to be converted into an .mp4, for which we are using ffmpeg.

The .mp4 output is the correct dimensions and duration, but blank (no images). Audio is not an issue as the original output has no audio.

ffmpeg version N-55020-g768e40b Copyright (c) 2000-2013 the FFmpeg developers
  built on Jul 28 2013 18:05:44 with gcc 4.7.3 (GCC)
  configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-avisynth --enable-bzlib --enable-fontconfig --e
nable-frei0r --enable-gnutls --enable-iconv --enable-libass --enable-libbluray --enable-libcaca --enable-libfreetype --enable
-libgsm --enable-libilbc --enable-libmodplug --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enab
le-libopenjpeg --enable-libopus --enable-librtmp --enable-libschroedinger --enable-libsoxr --enable-libspeex --enable-libtheo
ra --enable-libtwolame --enable-libvo-aacenc --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libx264 --en
able-libxavs --enable-libxvid --enable-zlib
  libavutil      52. 40.100 / 52. 40.100
  libavcodec     55. 19.100 / 55. 19.100
  libavformat    55. 12.102 / 55. 12.102
  libavdevice    55.  3.100 / 55.  3.100
  libavfilter     3. 81.103 /  3. 81.103
  libswscale      2.  4.100 /  2.  4.100
  libswresample   0. 17.103 /  0. 17.103
  libpostproc    52.  3.100 / 52.  3.100
Input #0, flv, from 'testWithAudio.flv':
  Metadata:
    canSeekToEnd    : true
    metadatacreator : FlvEncoder v0.9 Lee Felarca
  Duration: 00:00:44.77, start: 0.000000, bitrate: 56730 kb/s
    Stream #0:0: Video: flashsv, bgr24, 400x400, 30 tbr, 1k tbn, 1k tbc
    Stream #0:1: Audio: pcm_s16le, 44100 Hz, stereo, s16, 1411 kb/s
No pixel format specified, yuv444p for H.264 encoding chosen.
Use -pix_fmt yuv420p for compatibility with outdated media players.
[libx264 @ 00000000002e1da0] using cpu capabilities: MMX2 SSE2Fast SSEMisalign LZCNT
[libx264 @ 00000000002e1da0] profile High 4:4:4 Predictive, level 2.1, 4:4:4 8-bit
[libx264 @ 00000000002e1da0] 264 - core 135 r2345 f0c1c53 - H.264/MPEG-4 AVC codec - Copyleft 2003-2013 - http://www.videolan
.org/x264.html - options: cabac=1 ref=3 deblock=1:0:0 analyse=0x3:0x113 me=hex subme=7 psy=1 psy_rd=1.00:0.00 mixed_ref=1 me_
range=16 chroma_me=1 trellis=1 8x8dct=1 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=4 threads=1 lookahead_threads=1 sl
iced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=3 b_pyramid=2 b_adapt=1 b_bias=0 dire
ct=1 weightb=1 open_gop=0 weightp=2 keyint=250 keyint_min=25 scenecut=40 intra_refresh=0 rc_lookahead=40 rc=crf mbtree=1 crf=
23.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00
Output #0, mp4, to 'testWithAudio.mp4':
  Metadata:
    canSeekToEnd    : true
    metadatacreator : FlvEncoder v0.9 Lee Felarca
    encoder         : Lavf55.12.102
    Stream #0:0: Video: h264 (libx264) ([33][0][0][0] / 0x0021), yuv444p, 400x400, q=-1--1, 15360 tbn, 30 tbc
    Stream #0:1: Audio: aac (libvo_aacenc) ([64][0][0][0] / 0x0040), 44100 Hz, stereo, s16, 128 kb/s
Stream mapping:
  Stream #0:0 -> #0:0 (flashsv -> libx264)
  Stream #0:1 -> #0:1 (pcm_s16le -> libvo_aacenc)
Press [q] to stop, [?] for help
frame= 1343 fps= 25 q=29.0 Lsize=    2680kB time=00:00:44.70 bitrate= 491.2kbits/s
video:1943kB audio:691kB subtitle:0 global headers:0kB muxing overhead 1.756713%
[libx264 @ 00000000002e1da0] frame I:25    Avg QP:20.44  size: 14523
[libx264 @ 00000000002e1da0] frame P:614   Avg QP:23.20  size:  2319
[libx264 @ 00000000002e1da0] frame B:704   Avg QP:24.59  size:   287
[libx264 @ 00000000002e1da0] consecutive B-frames: 25.6% 11.0%  7.4% 56.0%
[libx264 @ 00000000002e1da0] mb I  I16..4: 17.6% 67.0% 15.3%
[libx264 @ 00000000002e1da0] mb P  I16..4:  7.6%  9.9%  0.8%  P16..4: 28.0%  8.3%  4.0%  0.0%  0.0%    skip:41.4%
[libx264 @ 00000000002e1da0] mb B  I16..4:  0.4%  0.5%  0.0%  B16..8: 16.3%  1.1%  0.1%  direct: 0.2%  skip:81.4%  L0:39.7% L
1:57.4% BI: 2.8%
[libx264 @ 00000000002e1da0] 8x8 transform intra:56.3% inter:85.5%
[libx264 @ 00000000002e1da0] coded y,u,v intra: 35.7% 17.0% 19.1% inter: 7.7% 3.8% 3.4%
[libx264 @ 00000000002e1da0] i16 v,h,dc,p: 26% 28% 17% 30%
[libx264 @ 00000000002e1da0] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu: 21% 21% 33%  4%  4%  5%  4%  4%  4%
[libx264 @ 00000000002e1da0] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 25% 21% 16%  5%  6%  9%  6%  6%  6%
[libx264 @ 00000000002e1da0] Weighted P-Frames: Y:6.5% UV:3.3%
[libx264 @ 00000000002e1da0] ref P L0: 56.8% 16.5% 18.2%  8.0%  0.6%
[libx264 @ 00000000002e1da0] ref B L0: 82.3% 14.1%  3.7%
[libx264 @ 00000000002e1da0] ref B L1: 93.7%  6.3%
[libx264 @ 00000000002e1da0] kb/s:355.47

Any ideas?

Answer 1

See the informational message:

No pixel format specified, yuv444p for H.264 encoding chosen.
Use -pix_fmt yuv420p for compatibility with outdated media players.

So, add -pix_fmt yuv420p and you should be fine.