Hello!
Recently I recieved a mp4 for playing. When I tried to play this file I
didn't hear any sound in some players (in ffplay sound worked). When I
looked at the metadata of this file (via ffprobe), I saw the following:
$ ffprobe 6kad_16_144p.mp4
ffprobe version 3.1.4 Copyright (c) 2007-2016 the FFmpeg developers
built with Apple LLVM version 8.0.0 (clang-800.0.38)
configuration: --prefix=/usr/local/Cellar/ffmpeg/3.1.4
--enable-shared --enable-pthreads --enable-gpl --enable-version3
--enable-hardcoded-tables --enable-avresample --cc=clang --host-cflags=
--host-ldflags= --enable-opencl --enable-libx264 --enable-libmp3lame
--enable-libxvid --enable-libfreetype --enable-libvorbis --enable-libvpx
--enable-libass --enable-libfdk-aac --enable-libopus --enable-libx265
--disable-lzma --enable-nonfree --enable-vda
libavutil 55. 28.100 / 55. 28.100
libavcodec 57. 48.101 / 57. 48.101
libavformat 57. 41.100 / 57. 41.100
libavdevice 57. 0.101 / 57. 0.101
libavfilter 6. 47.100 / 6. 47.100
libavresample 3. 0. 0 / 3. 0. 0
libswscale 4. 1.100 / 4. 1.100
libswresample 2. 1.100 / 2. 1.100
libpostproc 54. 0.100 / 54. 0.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '6kad_16_144p.mp4':
Metadata:
major_brand : isom
minor_version : 512
compatible_brands: isomiso2avc1mp41
creation_time : 2016-10-04 13:33:08
encoder : Lavf57.51.100
Duration: 00:22:49.90, start: 0.000000, bitrate: 335 kb/s
Stream #0:0(und): Video: h264 (Main) (avc1 / 0x31637661), yuv420p,
256x144 [SAR 1:1 DAR 16:9], 201 kb/s, 25 fps, 25 tbr, 12800 tbn, 50 tbc
(default)
Metadata:
creation_time : 2016-10-04 13:33:08
handler_name : VideoHandler
Stream #0:1(und): Audio: aac (mp4a / 0x6134706D), 48000 Hz, stereo,
fltp, 128 kb/s (default)
Metadata:
creation_time : 2016-10-04 13:33:08
handler_name : SoundHandler
Then I used mediainfo utility to see the metadata of the file:
$ mediainfo 6kad_16_144p.mp4
General
Complete name : 6kad_16_144p.mp4
Format : MPEG-4
Format profile : Base Media
Codec ID : isom (isom/iso2/avc1/mp41)
File size : 54.8 MiB
Duration : 22 min 49 s
Overall bit rate : 336 kb/s
Encoded date : UTC 2016-10-04 13:33:08
Tagged date : UTC 2016-10-04 13:33:08
Writing application : Lavf57.51.100
Video
ID : 1
Format : AVC
Format/Info : Advanced Video Codec
Format profile : [email protected]
Format settings, CABAC : Yes
Format settings, ReFrames : 2 frames
Codec ID : avc1
Codec ID/Info : Advanced Video Coding
Duration : 22 min 49 s
Bit rate : 200 kb/s
Width : 256 pixels
Height : 144 pixels
Display aspect ratio : 16:9
Frame rate mode : Constant
Frame rate : 25.000 FPS
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Progressive
Bits/(Pixel*Frame) : 0.217
Stream size : 32.9 MiB (60%)
Writing library : x264 core 148 r2721
Encoding settings : cabac=1 / ref=2 /
deblock=1:0:0 / analyse=0x1:0x131 / me=hex / subme=7 / psy=1 /
psy_rd=1.00:0.00 / mixed_ref=0 / me_range=16 / chroma_me=1 / trellis=1 /
8x8dct=0 / cqm=0 / deadzone=21,11 / fast_pskip=1 / chroma_qp_offset=-2 /
threads=3 / lookahead_threads=1 / sliced_threads=0 / nr=0 / decimate=1 /
interlaced=0 / bluray_compat=0 / constrained_intra=0 / bframes=3 /
b_pyramid=0 / b_adapt=1 / b_bias=0 / direct=0 / weightb=1 / open_gop=0 /
weightp=2 / keyint=250 / keyint_min=25 / scenecut=40 / intra_refresh=0 /
rc_lookahead=40 / rc=abr / mbtree=1 / bitrate=200 / ratetol=1.0 /
qcomp=0.60 / qpmin=10 / qpmax=69 / qpstep=4 / vbv_maxrate=8500 /
vbv_bufsize=24000 / nal_hrd=none / filler=0 / ip_ratio=1.40 / aq=3:1.00
Encoded date : UTC 2016-10-04 13:33:08
Tagged date : UTC 2016-10-04 13:33:08
Audio
ID : 2
Format : ER Parametric
Format/Info : Advanced Audio Codec
Codec ID : 40
Duration : 22 min 49 s
Bit rate mode : Constant
Bit rate : 128 kb/s
Channel(s) : 2 channels
Sampling rate : 7 350 Hz
Frame rate : 7.178 FPS (1024 spf)
Compression mode : Lossy
Stream size : 21.0 MiB (38%)
Default : Yes
Alternate group : 1
Encoded date : UTC 2016-10-04 13:33:08
Tagged date : UTC 2016-10-04 13:33:08
As you can see the "Sampling rate" in mediainfo is 7 350 Hz (it's
illegal value) while "Sampling rate" in ffprobe is 48000 Hz. I think
that the problem with the sound of this file has been caused by encoder
errors/misconfiguration. But it's very strange that ffrobe always shows
me 48000 Hz Sampling rate. Is this a bug or something else?
P.S. This mp4 file is available here https://yadi.sk/i/Ew77H8kiwpG7r
--
Sincerely,
Anatoliy V. Korostelev
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