On 09/04/2017 10:45 PM, Mark Thompson wrote:
On 04/09/17 21:34, Jorge Ramirez wrote:
On 09/04/2017 07:55 PM, Mark Thompson wrote:
On 04/09/17 18:01, Jorge Ramirez wrote:
On 09/04/2017 06:31 PM, Mark Thompson wrote:
On 04/09/17 17:00, Jorge Ramirez wrote:
On 09/03/2017 08:23 PM, Mark Thompson wrote:
On 03/09/17 17:54, Jorge Ramirez wrote:
On 09/03/2017 02:27 AM, Mark Thompson wrote:
+/* in ffmpeg there is a single thread could be queueing/dequeuing buffers so a
+ * timeout is * required when retrieving a frame in case the driver has not
received
+ * enough input * to start generating output.
+ *
+ * once decoding starts, the timeout should not be hit.
This seems like it could introduce a significant delay on startup for no good
reason. Can you instead just queue packets until either you run out of input
buffers or a nonblocking dequeue succeeds?
(I might need to think more about how the semantics of this work.)
if the decoder needs 4 blocks, the delay is 200ms, if it is 10 blocks, that is
500ms which doesn't seem too significant? when I test I barely notice the
difference with respect to using the h264 codec (or any of the others in fact)
the best solution would be to be able to block until the capture queue has
frames ready but for that we would need another thread inputting independently
on the other queue...does ffmpeg allow for this? separate threads for input and
output?
Since the API is nonblocking, you can just return EAGAIN from receive_frame if
there are any free buffers (to request more input). You would then only block
waiting for output if there is no more input (end of stream) or there aren't
any free buffers (so no more input could be accepted). Ideally there would
then be no timeouts at all except in error cases.
sure, can do that as well, not a problem.
the encoding API doesnt seem to allow for this though: once it retrieves a
valid frame it appears to keep on reading them without inputing others (this
causes teh capture queue to block for ever)
is this intentional or is it a bug?
The encode API should be identical to the decode API with frames/packets
swapped (see docs in avcodec.h).
If you have an lavc-using program which calls receive_packet() repeatedly after
it has returned EAGAIN and never calls send_packet() then that program is wrong.
thanks for the prompt answer.
yes I am just using the ffmpeg binary to encode a stream; however once a valid
encoded packet is returned, send_frame is not ever called again unless I
return EAGAIN from v4l2m2m_receive_packet.
But I cant return EAGAIN on receive_packet while I am blocked waiting for data
which will never arrive (since send_frame is not executing)
seems to me like a bug in ffmeg but I dont like to question baseline code with
obvious bugs (this seems to simple to be real)
anyway looking at the function do_video_out() the code seems strange but it
explains why my encoding blocks unless I timeout and return EAGAIN.
ret = avcodec_send_frame(enc, in_picture);
if (ret < 0)
goto error;
while (1) {
ret = avcodec_receive_packet(enc, &pkt);
update_benchmark("encode_video %d.%d", ost->file_index,
ost->index);
if (ret == AVERROR(EAGAIN))
break;
if (ret < 0)
goto error;
if (debug_ts) {
av_log(NULL, AV_LOG_INFO, "encoder -> type:video "
"pkt_pts:%s pkt_pts_time:%s pkt_dts:%s
pkt_dts_time:%s\n",
av_ts2str(pkt.pts), av_ts2timestr(pkt.pts,
&enc->time_base),
av_ts2str(pkt.dts), av_ts2timestr(pkt.dts,
&enc->time_base));
}
if (pkt.pts == AV_NOPTS_VALUE && !(enc->codec->capabilities &
AV_CODEC_CAP_DELAY))
pkt.pts = ost->sync_opts;
av_packet_rescale_ts(&pkt, enc->time_base, ost->mux_timebase);
if (debug_ts) {
av_log(NULL, AV_LOG_INFO, "encoder -> type:video "
"pkt_pts:%s pkt_pts_time:%s pkt_dts:%s
pkt_dts_time:%s\n",
av_ts2str(pkt.pts), av_ts2timestr(pkt.pts,
&ost->mux_timebase),
av_ts2str(pkt.dts), av_ts2timestr(pkt.dts,
&ost->mux_timebase));
}
frame_size = pkt.size;
output_packet(of, &pkt, ost, 0);
/* if two pass, output log */
if (ost->logfile && enc->stats_out) {
fprintf(ost->logfile, "%s", enc->stats_out);
}
}
}
so if I queue 20 frames in the output queue and the allow frames to be
dequeued, all of them are dequeued at once and then the code just blocks
waiting for more input...
does the above look ok to you?
Yes: send_frame() is always callable once, and then receive_packet() is
callable repeatedly until it returns EAGAIN; once it does, send_frame() is
necessarily callable again.
Can you offer a sequence of valid returns from the lavc API which would break
it? (Ignoring what the implementation behind it actually is for a moment.)
yes, just the code I have in the patch I am preparing for v9 for instance where
I remove the timeout.
https://github.com/ldts/FFmpeg/blob/patches/v9/libavcodec/v4l2_m2m_enc.c#L267
encoding just blocks.
After having queued all input buffers it dequeues the first packet ...but then
it just and keeps on trying to do that for ever since we block for output ready
and never send another frame.
decoding works as expected.
https://github.com/ldts/FFmpeg/blob/patches/v9/libavcodec/v4l2_m2m_dec.c#L148
There is too much code there for me to follow exactly what the sequence is
without hardware to run it on. Could you post an ordered list of all of the
avcodec_send_frame() and avcodec_receive_packet() calls and results which
result in this deadlock? If it is an error in ffmpeg.c then those calls must
be violating the API contact somehow independent of the actual implementation
being used, and that could be verified and fixed without the v4l2 encoder.
sorry for the rather long trace (I thought it was better than missing info or
using http://haste.bin or similar)
linaro@db820 raw]$ cat encode.h264.sh
ffmpeg -loglevel debug -f rawvideo -pix_fmt nv12 -s:v 1280:720 -r 25 -i
~/Videos/raw/freeway.yuv -c:v h264_v4l2m2m out/out.h264.mp4
linaro@db820 raw]$ ./encode.h264.sh
~/Src/git.zoltan.ffmpeg/ffmpeg -loglevel debug -f rawvideo -pix_fmt nv12 -s:v
1280:720 -r 25 -i ~/Videos/raw/freeway.yuv -c:v h264_v4l2m2m out/out.h264.mp4
-loglevel debug -f rawvideo -pix_fmt nv12 -s:v 1280:720 -r 25 -i
~/Videos/raw/freeway.yuv -c:v h264_v4l2m2m out/out.h264.mp4
ffmpeg version N-87159-ga1e41bc747 Copyright (c) 2000-2017 the FFmpeg developers
built with gcc 6.3.0 (Debian 6.3.0-21) 20170628
configuration: --disable-optimizations --disable-stripping
libavutil 55. 74.100 / 55. 74.100
libavcodec 57.104.101 / 57.104.101
libavformat 57. 80.100 / 57. 80.100
libavdevice 57. 8.100 / 57. 8.100
libavfilter 6.101.100 / 6.101.100
libswscale 4. 7.103 / 4. 7.103
libswresample 2. 8.100 / 2. 8.100
Splitting the commandline.
Reading option '-loglevel' ... matched as option 'loglevel' (set logging level)
with argument 'debug'.
Reading option '-f' ... matched as option 'f' (force format) with argument
'rawvideo'.
Reading option '-pix_fmt' ... matched as option 'pix_fmt' (set pixel format)
with argument 'nv12'.
Reading option '-s:v' ... matched as option 's' (set frame size (WxH or
abbreviation)) with argument '1280:720'.
Reading option '-r' ... matched as option 'r' (set frame rate (Hz value,
fraction or abbreviation)) with argument '25'.
Reading option '-i' ... matched as input url with argument
'/home/linaro/Videos/raw/freeway.yuv'.
Reading option '-c:v' ... matched as option 'c' (codec name) with argument
'h264_v4l2m2m'.
Reading option 'out/out.h264.mp4' ... matched as output url.
Finished splitting the commandline.
Parsing a group of options: global .
Applying option loglevel (set logging level) with argument debug.
Successfully parsed a group of options.
Parsing a group of options: input url /home/linaro/Videos/raw/freeway.yuv.
Applying option f (force format) with argument rawvideo.
Applying option pix_fmt (set pixel format) with argument nv12.
Applying option s:v (set frame size (WxH or abbreviation)) with argument
1280:720.
Applying option r (set frame rate (Hz value, fraction or abbreviation)) with
argument 25.
Successfully parsed a group of options.
Opening an input file: /home/linaro/Videos/raw/freeway.yuv.
[rawvideo @ 0xaaaafee46490] Opening '/home/linaro/Videos/raw/freeway.yuv' for
reading
[file @ 0xaaaafee46d10] Setting default whitelist 'file,crypto'
[rawvideo @ 0xaaaafee46490] Before avformat_find_stream_info() pos: 0 bytes
read:32768 seeks:0 nb_streams:1
[rawvideo @ 0xaaaafee46490] All info found
[rawvideo @ 0xaaaafee46490] Estimating duration from bitrate, this may be
inaccurate
[rawvideo @ 0xaaaafee46490] After avformat_find_stream_info() pos: 1382400
bytes read:1382400 seeks:0 frames:1
Input #0, rawvideo, from '/home/linaro/Videos/raw/freeway.yuv':
Duration: 00:00:09.28, start: 0.000000, bitrate: 276480 kb/s
Stream #0:0, 1, 1/25: Video: rawvideo, 1 reference frame (NV12 /
0x3231564E), nv12, 1280x720, 0/1, 276480 kb/s, 25 tbr, 25 tbn, 25 tbc
Successfully opened the file.
Parsing a group of options: output url out/out.h264.mp4.
Applying option c:v (codec name) with argument h264_v4l2m2m.
Successfully parsed a group of options.
Opening an output file: out/out.h264.mp4.
[file @ 0xaaaafee53930] Setting default whitelist 'file,crypto'
Successfully opened the file.
Stream mapping:
Stream #0:0 -> #0:0 (rawvideo (native) -> h264 (h264_v4l2m2m))
Press [q] to stop, [?] for help
cur_dts is invalid (this is harmless if it occurs once at the start per stream)
[rawvideo @ 0xaaaafee500a0] PACKET SIZE: 1382400, STRIDE: 1920
detected 4 logical cores
[graph 0 input from stream 0:0 @ 0xaaaafee55430] Setting 'video_size' to value
'1280x720'
[graph 0 input from stream 0:0 @ 0xaaaafee55430] Setting 'pix_fmt' to value '25'
[graph 0 input from stream 0:0 @ 0xaaaafee55430] Setting 'time_base' to value
'1/25'
[graph 0 input from stream 0:0 @ 0xaaaafee55430] Setting 'pixel_aspect' to
value '0/1'
[graph 0 input from stream 0:0 @ 0xaaaafee55430] Setting 'sws_param' to value
'flags=2'
[graph 0 input from stream 0:0 @ 0xaaaafee55430] Setting 'frame_rate' to value
'25/1'
[graph 0 input from stream 0:0 @ 0xaaaafee55430] w:1280 h:720 pixfmt:nv12
tb:1/25 fr:25/1 sar:0/1 sws_param:flags=2
[AVFilterGraph @ 0xaaaafee47080] query_formats: 3 queried, 2 merged, 0 already
done, 0 delayed
[h264_v4l2m2m @ 0xaaaafee51b70] probing device /dev/video1
[h264_v4l2m2m @ 0xaaaafee51b70] driver 'qcom-venus' on card 'Qualcomm Venus
video decoder'
[h264_v4l2m2m @ 0xaaaafee51b70] output format not supported
[h264_v4l2m2m @ 0xaaaafee51b70] probing device /dev/video0
[h264_v4l2m2m @ 0xaaaafee51b70] driver 'qcom-venus' on card 'Qualcomm Venus
video encoder'
[h264_v4l2m2m @ 0xaaaafee51b70] Using device /dev/video0
[h264_v4l2m2m @ 0xaaaafee51b70] driver 'qcom-venus' on card 'Qualcomm Venus
video encoder'
[h264_v4l2m2m @ 0xaaaafee51b70] v4l2_out queuing 16 buffers
[h264_v4l2m2m @ 0xaaaafee51b70] v4l2_cap queuing 4 buffers
[h264_v4l2m2m @ 0xaaaafee51b70] Encoder: number of B-frames = 0
[h264_v4l2m2m @ 0xaaaafee51b70] Encoder: header mode = 0
[h264_v4l2m2m @ 0xaaaafee51b70] Encoder: bit rate = 200000
[h264_v4l2m2m @ 0xaaaafee51b70] Encoder: gop size = 12
[h264_v4l2m2m @ 0xaaaafee51b70] Encoder Context: id (28), profile (-99), frame
rate(25/1), number b-frames (0), gop size (12), bit rate (200000), qmin (2),
qmax (31)
[h264_v4l2m2m @ 0xaaaafee51b70] h264 profile not found
[h264_v4l2m2m @ 0xaaaafee51b70] Encoder adjusted: qmin (0), qmax (51)
[h264_v4l2m2m @ 0xaaaafee51b70] Encoder: minimum video quantizer scale = 0
[h264_v4l2m2m @ 0xaaaafee51b70] Encoder: maximum video quantizer scale = 51
Output #0, mp4, to 'out/out.h264.mp4':
Metadata:
encoder : Lavf57.80.100
Stream #0:0, 0, 1/12800: Video: h264 (h264_v4l2m2m), 1 reference frame
(avc1 / 0x31637661), nv12, 1280x720, 0/1, q=2-31, 200 kb/s, 25 fps, 12800 tbn,
25 tbc
Metadata:
encoder : Lavc57.104.101 h264_v4l2m2m
Clipping frame in rate conversion by 0.000008
[h264_v4l2m2m @ 0xaaaafee51b70] enqued raw frame 0
[rawvideo @ 0xaaaafee500a0] PACKET SIZE: 1382400, STRIDE: 1920
[h264_v4l2m2m @ 0xaaaafee51b70] enqued raw frame 1
[rawvideo @ 0xaaaafee500a0] PACKET SIZE: 1382400, STRIDE: 1920
[h264_v4l2m2m @ 0xaaaafee51b70] enqued raw frame 2
[rawvideo @ 0xaaaafee500a0] PACKET SIZE: 1382400, STRIDE: 1920
[h264_v4l2m2m @ 0xaaaafee51b70] enqued raw frame 3
[rawvideo @ 0xaaaafee500a0] PACKET SIZE: 1382400, STRIDE: 1920
[h264_v4l2m2m @ 0xaaaafee51b70] enqued raw frame 4
[rawvideo @ 0xaaaafee500a0] PACKET SIZE: 1382400, STRIDE: 1920
[h264_v4l2m2m @ 0xaaaafee51b70] enqued raw frame 5
[rawvideo @ 0xaaaafee500a0] PACKET SIZE: 1382400, STRIDE: 1920
[h264_v4l2m2m @ 0xaaaafee51b70] enqued raw frame 6
[rawvideo @ 0xaaaafee500a0] PACKET SIZE: 1382400, STRIDE: 1920
[h264_v4l2m2m @ 0xaaaafee51b70] enqued raw frame 7
[rawvideo @ 0xaaaafee500a0] PACKET SIZE: 1382400, STRIDE: 1920
[h264_v4l2m2m @ 0xaaaafee51b70] enqued raw frame 8
[rawvideo @ 0xaaaafee500a0] PACKET SIZE: 1382400, STRIDE: 1920
[h264_v4l2m2m @ 0xaaaafee51b70] enqued raw frame 9
[rawvideo @ 0xaaaafee500a0] PACKET SIZE: 1382400, STRIDE: 1920
[h264_v4l2m2m @ 0xaaaafee51b70] enqued raw frame 10
[rawvideo @ 0xaaaafee500a0] PACKET SIZE: 1382400, STRIDE: 1920
[h264_v4l2m2m @ 0xaaaafee51b70] enqued raw frame 11
[rawvideo @ 0xaaaafee500a0] PACKET SIZE: 1382400, STRIDE: 1920
[h264_v4l2m2m @ 0xaaaafee51b70] enqued raw frame 12
[rawvideo @ 0xaaaafee500a0] PACKET SIZE: 1382400, STRIDE: 1920
[h264_v4l2m2m @ 0xaaaafee51b70] enqued raw frame 13
[rawvideo @ 0xaaaafee500a0] PACKET SIZE: 1382400, STRIDE: 1920
[h264_v4l2m2m @ 0xaaaafee51b70] enqued raw frame 14
[rawvideo @ 0xaaaafee500a0] PACKET SIZE: 1382400, STRIDE: 1920
[h264_v4l2m2m @ 0xaaaafee51b70] enqued raw frame 15
[rawvideo @ 0xaaaafee500a0] PACKET SIZE: 1382400, STRIDE: 1920
[h264_v4l2m2m @ 0xaaaafee51b70] enqued raw frame 16
[h264_v4l2m2m @ 0xaaaafee51b70] dequeued encoded packet 0
[h264_v4l2m2m @ 0xaaaafee51b70] dequeued encoded packet 1
[h264_v4l2m2m @ 0xaaaafee51b70] dequeued encoded packet 2
[h264_v4l2m2m @ 0xaaaafee51b70] dequeued encoded packet 3
[h264_v4l2m2m @ 0xaaaafee51b70] dequeued encoded packet 4
[h264_v4l2m2m @ 0xaaaafee51b70] dequeued encoded packet 5
[h264_v4l2m2m @ 0xaaaafee51b70] dequeued encoded packet 6
[h264_v4l2m2m @ 0xaaaafee51b70] dequeued encoded packet 7
[h264_v4l2m2m @ 0xaaaafee51b70] dequeued encoded packet 8
[h264_v4l2m2m @ 0xaaaafee51b70] dequeued encoded packet 9
[h264_v4l2m2m @ 0xaaaafee51b70] dequeued encoded packet 10
[h264_v4l2m2m @ 0xaaaafee51b70] dequeued encoded packet 11
[h264_v4l2m2m @ 0xaaaafee51b70] dequeued encoded packet 12
[h264_v4l2m2m @ 0xaaaafee51b70] dequeued encoded packet 13
[h264_v4l2m2m @ 0xaaaafee51b70] dequeued encoded packet 14
[h264_v4l2m2m @ 0xaaaafee51b70] dequeued encoded packet 15
[h264_v4l2m2m @ 0xaaaafee51b70] dequeued encoded packet 16
[at this point it blocks for ever since it has consumed all the input and we
are blocking)
The code in the encoder:
static int v4l2m2m_send_frame(AVCodecContext *avctx, const AVFrame *frame)
{
V4L2m2mContext *s = avctx->priv_data;
V4L2Context *const capture = &s->capture;
V4L2Context *const output = &s->output;
int ret;
static int cnt = 0;
if (!output->streamon) {
ret = ff_v4l2_context_set_status(output, VIDIOC_STREAMON);
if (ret) {
av_log(avctx, AV_LOG_ERROR, "VIDIOC_STREAMOFF failed on output
context\n");
return ret;
}
}
if (!capture->streamon) {
ret = ff_v4l2_context_set_status(capture, VIDIOC_STREAMON);
if (ret) {
av_log(avctx, AV_LOG_ERROR, "VIDIOC_STREAMON failed on capture
context\n");
return ret;
}
}
ret = ff_v4l2_enqueue_frame(output, frame);
if (!ret) {
av_log(avctx, AV_LOG_ERROR, "enqued raw frame %d\n", cnt++);
}
return ret;
}
/* Send and receive frame happen on the same thread, hence the need for a
polling timeout */
static int v4l2m2m_receive_packet(AVCodecContext *avctx, AVPacket *avpkt)
{
V4L2m2mContext *s = avctx->priv_data;
V4L2Context *const capture = &s->capture;
V4L2Context *const output = &s->output;
unsigned int timeout = -1; /* block for ever until packets are ready to
dequeue */
static int cnt = 0;
int ret;
if (s->draining)
goto dequeue;
if (!s->data_queued) {
if (output->ops.get_buffer(output))
return AVERROR(EAGAIN);
else s->data_queued = 1;
}
dequeue:
ret = ff_v4l2_dequeue_packet(capture, avpkt, timeout);
if (!ret)
av_log(avctx, AV_LOG_ERROR, "dequeued encoded packet %d\n", cnt++);
return ret;
}
