I have two named pipes, audio_conv and video, for s16le and h264 streams, respectively. I want to convert them to webm format on fly. Data to these pipes proceeds from my application, that parses proprietary format and converts audio. But sometimes there is no audio in incoming stream, and I can't easily determine it on initialization stage.
When I pass both audio and video, it is OK, but when there is no audio, corresponding pipe is empty and, as I understand, ffmpeg stops converting video and awaits for some audio data.
Command I use:
ffmpeg -v debug -probesize 10000 -r 12 -analyzeduration 0 -vsync 0 -async 0 -i video -f s16le -ar 8000 -analyzeduration 0 -channel_layout mono -i audio_conv -f webm - | ffplay -
From ffmpeg log:
Successfully parsed a group of options.
Opening an input file: video.
[h264 @ 0x23bf460] Format h264 probed with size=2048 and score=51
[h264 @ 0x23bf460] Before avformat_find_stream_info() pos: 0 bytes read:2910 seeks:0
[h264 @ 0x23bf460] Probe buffer size limit of 10000 bytes reached
[h264 @ 0x23bf460] Stream #0: not enough frames to estimate rate; consider increasing probesize
[h264 @ 0x23bf460] decoding for stream 0 failed
[h264 @ 0x23bf460] After avformat_find_stream_info() pos: 15805 bytes read:17153 seeks:0 frames:1
Input #0, h264, from 'video':
Duration: N/A, bitrate: N/A
Stream #0:0, 1, 1/1200000: Video: h264 (Baseline), 1 reference frame, yuv420p(left), 704x576, 1/50, 25 tbr, 1200k tbn, 50 tbc
Successfully opened the file.
Parsing a group of options: input file audio_conv.
Applying option f (force format) with argument s16le.
Applying option ar (set audio sampling rate (in Hz)) with argument 8000.
Applying option channel_layout (set channel layout) with argument mono.
Successfully parsed a group of options.
Opening an input file: audio_conv.
After that I can see that video stream is passed to ffmpeg, but after some time it accidentally stops. And then, after kill'ing ffmpeg process, it outputs:
[s16le @ 0x16a8060] Before avformat_find_stream_info() pos: 0 bytes read:0 seeks:0
[s16le @ 0x16a8060] After avformat_find_stream_info() pos: 0 bytes read:0 seeks:0 frames:0
Input #1, s16le, from 'audio_conv':
Duration: N/A, bitrate: 128 kb/s
Stream #1:0, 0, 1/8000: Audio: pcm_s16le, 8000 Hz, mono, s16, 128 kb/s
Successfully opened the file.
Parsing a group of options: output file -.
Applying option f (force format) with argument webm.
Successfully parsed a group of options.
Opening an output file: -.
Successfully opened the file.
detected 4 logical cores 0 aq= 0KB vq= 0KB sq= 0B f=0/0
[graph 0 input from stream 0:0 @ 0x16cf220] Setting 'video_size' to value '704x576'
[graph 0 input from stream 0:0 @ 0x16cf220] Setting 'pix_fmt' to value '0'
[graph 0 input from stream 0:0 @ 0x16cf220] Setting 'time_base' to value '1/12'
[graph 0 input from stream 0:0 @ 0x16cf220] Setting 'pixel_aspect' to value '0/1'
[graph 0 input from stream 0:0 @ 0x16cf220] Setting 'sws_param' to value 'flags=2'
[graph 0 input from stream 0:0 @ 0x16cf220] Setting 'frame_rate' to value '12/1'
[graph 0 input from stream 0:0 @ 0x16cf220] w:704 h:576 pixfmt:yuv420p tb:1/12 fr:12/1 sar:0/1 sws_param:flags=2
[force CFR for input from stream 0:0 @ 0x16a95a0] Setting 'expr' to value 'N'
[format @ 0x16a6160] compat: called with args=[yuv420p|yuv422p|yuv440p|yuv444p]
[format @ 0x16a6160] Setting 'pix_fmts' to value 'yuv420p|yuv422p|yuv440p|yuv444p'
[AVFilterGraph @ 0x16cc400] query_formats: 5 queried, 4 merged, 0 already done, 0 delayed
[graph 0 input from stream 0:0 @ 0x16cf220] TB:0.083333 FRAME_RATE:12.000000 SAMPLE_RATE:nan
[graph 1 input from stream 1:0 @ 0x16aa8c0] Setting 'time_base' to value '1/8000'
[graph 1 input from stream 1:0 @ 0x16aa8c0] Setting 'sample_rate' to value '8000'
[graph 1 input from stream 1:0 @ 0x16aa8c0] Setting 'sample_fmt' to value 's16'
[graph 1 input from stream 1:0 @ 0x16aa8c0] Setting 'channel_layout' to value '0x4'
[graph 1 input from stream 1:0 @ 0x16aa8c0] tb:1/8000 samplefmt:s16 samplerate:8000 chlayout:0x4
[audio format for output stream 0:1 @ 0x16aa760] Setting 'sample_fmts' to value 's16|flt'
[audio format for output stream 0:1 @ 0x16aa760] Setting 'sample_rates' to value '48000|24000|16000|12000|8000'
[audio format for output stream 0:1 @ 0x16aa760] Setting 'channel_layouts' to value '0x4|0x3|0x7|0x33|0x37|0x3f|0x70f|0x63f'
[AVFilterGraph @ 0x16ab920] query_formats: 4 queried, 9 merged, 0 already done, 0 delayed
[libvpx-vp9 @ 0x16ce760] v1.5.0
[libvpx-vp9 @ 0x16ce760] --prefix=/usr --enable-pic --enable-shared --disable-install-bins --disable-install-srcs --size-limit=16384x16384 --enable-postproc --enable-multi-res-encoding --enable-temporal-denoising --enable-vp9-temporal-denoising --enable-vp9-postproc --target=x86_64-linux-gcc
[libvpx-vp9 @ 0x16ce760] vpx_codec_enc_cfg
[libvpx-vp9 @ 0x16ce760] generic settings
g_usage: 0
g_threads: 8
g_profile: 0
g_w: 320
g_h: 240
g_bit_depth: 8
g_input_bit_depth: 8
g_timebase: {1/30}
g_error_resilient: 0
g_pass: 0
g_lag_in_frames: 25
[libvpx-vp9 @ 0x16ce760] rate control settings
rc_dropframe_thresh: 0
rc_resize_allowed: 0
rc_resize_up_thresh: 60
rc_resize_down_thresh: 30
rc_end_usage: 0
rc_twopass_stats_in: (nil)(0)
rc_target_bitrate: 256
[libvpx-vp9 @ 0x16ce760] quantizer settings
rc_min_quantizer: 0
rc_max_quantizer: 63
[libvpx-vp9 @ 0x16ce760] bitrate tolerance
rc_undershoot_pct: 25
rc_overshoot_pct: 25
[libvpx-vp9 @ 0x16ce760] decoder buffer model
rc_buf_sz: 6000
rc_buf_initial_sz: 4000
rc_buf_optimal_sz: 5000
[libvpx-vp9 @ 0x16ce760] 2 pass rate control settings
rc_2pass_vbr_bias_pct: 50
rc_2pass_vbr_minsection_pct: 0
rc_2pass_vbr_maxsection_pct: 2000
[libvpx-vp9 @ 0x16ce760] keyframing settings
kf_mode: 1
kf_min_dist: 0
kf_max_dist: 9999
[libvpx-vp9 @ 0x16ce760]
[libvpx-vp9 @ 0x16ce760] vpx_codec_enc_cfg
[libvpx-vp9 @ 0x16ce760] generic settings
g_usage: 0
g_threads: 0
g_profile: 0
g_w: 704
g_h: 576
g_bit_depth: 8
g_input_bit_depth: 8
g_timebase: {1/12}
g_error_resilient: 0
g_pass: 0
g_lag_in_frames: 25
[libvpx-vp9 @ 0x16ce760] rate control settings
rc_dropframe_thresh: 0
rc_resize_allowed: 0
rc_resize_up_thresh: 60
rc_resize_down_thresh: 30
rc_end_usage: 0
rc_twopass_stats_in: (nil)(0)
rc_target_bitrate: 200
[libvpx-vp9 @ 0x16ce760] quantizer settings
rc_min_quantizer: 0
rc_max_quantizer: 63
[libvpx-vp9 @ 0x16ce760] bitrate tolerance
rc_undershoot_pct: 25
rc_overshoot_pct: 25
[libvpx-vp9 @ 0x16ce760] decoder buffer model
rc_buf_sz: 6000
rc_buf_initial_sz: 4000
rc_buf_optimal_sz: 5000
[libvpx-vp9 @ 0x16ce760] 2 pass rate control settings
rc_2pass_vbr_bias_pct: 50
rc_2pass_vbr_minsection_pct: 0
rc_2pass_vbr_maxsection_pct: 2000
[libvpx-vp9 @ 0x16ce760] keyframing settings
kf_mode: 1
kf_min_dist: 0
kf_max_dist: 9999
[libvpx-vp9 @ 0x16ce760]
[libvpx-vp9 @ 0x16ce760] vpx_codec_control
[libvpx-vp9 @ 0x16ce760] VP8E_SET_CPUUSED: 1
[libvpx-vp9 @ 0x16ce760] VP8E_SET_ARNR_MAXFRAMES: 0
[libvpx-vp9 @ 0x16ce760] VP8E_SET_ARNR_STRENGTH: 3
[libvpx-vp9 @ 0x16ce760] VP8E_SET_ARNR_TYPE: 3
[libvpx-vp9 @ 0x16ce760] VP8E_SET_STATIC_THRESHOLD: 0
[libvpx-vp9 @ 0x16ce760] VP9E_SET_COLOR_SPACE: 0
[libvpx-vp9 @ 0x16ce760] Using deadline: 1000000
[libopus @ 0x16cfda0] No bit rate set. Defaulting to 64000 bps.
Is there is a way to tell ffmpeg to skip audio if there is no input data?
