How to encode H.264 video using FFmpeg C API and t

2019-03-21 03:36发布

问题:

I'm trying to encode a H.264 video with the FFMPEG C API. I have successfully compiled and executed the decoding/encoding example provided by FFMPEG.

The problem I'm facing is that the .mpg file (encoded with AV_CODEC_ID_MPEG1VIDEO) the example creates works. Windows creates a thumbnail and everything. On the other hand the .h264 (encoded with AV_CODEC_ID_H264) file does not. When I try to play the file in VLC the play/pause button just flickers, no thumbnail in windows, no nothing.

During encoding libx264 reports the following:

[libx264 @ 004b81a0] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX
[libx264 @ 004b81a0] profile High, level 1.3
[libx264 @ 004b81a0] frame I:3     Avg QP:26.79  size:  2116
[libx264 @ 004b81a0] frame P:12    Avg QP:26.60  size:   789
[libx264 @ 004b81a0] frame B:10    Avg QP:31.39  size:   499
[libx264 @ 004b81a0] consecutive B-frames: 20.0% 80.0%
[libx264 @ 004b81a0] mb I  I16..4: 78.3% 11.6% 10.1%
[libx264 @ 004b81a0] mb P  I16..4: 77.4%  0.6%  0.1%  P16..4: 20.3%  0.7%  0.9%  0.0%  0.0%    skip: 0.0%
[libx264 @ 004b81a0] mb B  I16..4:  0.0%  0.0%  0.0%  B16..8:  9.4%  0.2%  0.0%  direct:11.0%  skip:79.4%  L0:25.4% L1:35.4% BI:39.2%
[libx264 @ 004b81a0] final ratefactor: 17.03
[libx264 @ 004b81a0] 8x8 transform intra:3.4% inter:31.3%
[libx264 @ 004b81a0] direct mvs  spatial:0.0% temporal:100.0%
[libx264 @ 004b81a0] coded y,uvDC,uvAC intra: 4.4% 35.8% 1.6% inter: 1.3% 34.5% 9.5%
[libx264 @ 004b81a0] i16 v,h,dc,p:  0%  0%  0% 100%
[libx264 @ 004b81a0] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu:  7% 20% 17% 49%  0%  0%  0%  1%  6%
[libx264 @ 004b81a0] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 14%  7% 18% 45%  2%  7%  2%  3%  2%
[libx264 @ 004b81a0] i8c dc,h,v,p:  2%  6%  4% 88%
[libx264 @ 004b81a0] Weighted P-Frames: Y:0.0% UV:0.0%
[libx264 @ 004b81a0] ref P L0: 95.6%  1.6%  2.2%  0.5%  0.2%
[libx264 @ 004b81a0] ref B L0: 67.5% 28.5%  3.2%  0.8%
[libx264 @ 004b81a0] kb/s:166.45

"ffprobe.exe test.h264 -show_streams" returns

[STREAM]
index=0
codec_name=h264
codec_long_name=H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10
profile=High
codec_type=video
codec_time_base=1/50
codec_tag_string=[0][0][0][0]
codec_tag=0x0000
width=352
height=288
has_b_frames=1
sample_aspect_ratio=0:1
display_aspect_ratio=0:1
pix_fmt=yuv420p
level=13
timecode=N/A
id=N/A
r_frame_rate=50/2
avg_frame_rate=25/1
time_base=1/1200000
start_pts=N/A
start_time=N/A
duration_ts=N/A
duration=N/A
bit_rate=N/A
nb_frames=N/A
nb_read_frames=N/A
nb_read_packets=N/A
DISPOSITION:default=0
DISPOSITION:dub=0
DISPOSITION:original=0
DISPOSITION:comment=0
DISPOSITION:lyrics=0
DISPOSITION:karaoke=0
DISPOSITION:forced=0
DISPOSITION:hearing_impaired=0
DISPOSITION:visual_impaired=0
DISPOSITION:clean_effects=0
DISPOSITION:attached_pic=0
[/STREAM]

There you can see:

start_time=N/A
duration_ts=N/A
duration=N/A

I have tried countless changes to the AVCodecContext and multitude of parameters options to av_opt_set function. Still no luck getting a working H.264 video. I have even tried different builds of FFmpeg. No luck.

I'm using the "FFmpeg git-0fb64da 32-bit Dev" build from Zeranoe and MinGw 4.7.2

回答1:

Your problem probably is not encoding itself but the fact that you output raw H.264 stream (I suppose you used AnnexB format) without any muxing. Most of players expect H.264 in some container (like MKV, MP4 or FLV) and do not support playing of raw H.264 streams. For players using DirectShow filters (like MPC-HC / WMP) it also needs raw H.264 AnnexB demuxer before decoder. Try to mux this output to MKV with MKVToolnix and test resulting file.



回答2:

As mentioned by nobody555, maybe your VLC simply cannot open that file because it is a raw stream.

Alternatives are listed at: https://superuser.com/questions/261774/converting-or-playing-a-264-video-file

ffplay is an option, but it also works on VLC 2.2.1, Ubnuntu 15.10.

Also consider the example: https://github.com/FFmpeg/FFmpeg/blob/n3.0/doc/examples/muxing.c which generates a container format instead of a raw stream.