[streaming] H.264 stream with severe packet loss

[Neeraj Jayaswal]

Hi everyone
I am newbie to streaming and codecs
Does ffmpeg/libavcodec have error concealment in case of packet loss for a
H.264 stream.
I am running a standalone H.264 stream with known packet losses and VLC
player displays the following messages
The stream does not  contain any timing info.



*main debug: adding playlist item `E:\Shailesh\H264_DePack_OLD\Copy of
H264_pkt_loss.264' ( E:\Shailesh\H264_DePack_OLD\Copy of H264_pkt_loss.264 )

main debug: creating new input thread
main debug: waiting for thread completion
main warning: drive letter E: found in source
main debug: `E:\Shailesh\H264_DePack_OLD\Copy of H264_pkt_loss.264' gives
access `' demux `' path `E:\Shailesh\H264_DePack_OLD\Copy of
H264_pkt_loss.264'
main debug: creating demux: access='' demux=''
path='E:\Shailesh\H264_DePack_OLD\Copy of H264_pkt_loss.264'
main debug: looking for access_demux module: 1 candidate
main debug: thread 3768 (input) created at priority 1
(src/input/input.c:230)
main debug: creating access '' path='E:\Shailesh\H264_DePack_OLD\Copy of
H264_pkt_loss.264'
main debug: looking for access2 module: 5 candidates
vcd debug: trying .cue file: E:\Shailesh\H264_DePack_OLD\Copy of
H264_pkt_loss.cue
access_file debug: opening file `E:\Shailesh\H264_DePack_OLD\Copy of
H264_pkt_loss.264'
main debug: using access2 module "access_file"
main debug: pre buffering
main debug: received first data for our buffer
main debug: prebuffering done 1408981 bytes in 0s - 374410 kbytes/s
main debug: creating demux: access='' demux=''
path='E:\Shailesh\H264_DePack_OLD\Copy of H264_pkt_loss.264'
main debug: looking for demux2 module: 40 candidates
ffmpeg debug: detected format: h264
main debug: selecting program id=0
ffmpeg debug: adding es: video codec = h264
ffmpeg debug: AVFormat supported stream
ffmpeg debug:     - format = h264 (raw H264 video format)
ffmpeg debug:     - start time = -1
ffmpeg debug:     - duration = -1
main debug: using demux2 module "ffmpeg"
main debug: looking for a subtitle file in E:\Shailesh\H264_DePack_OLD\
main debug: looking for decoder module: 26 candidates
ffmpeg debug: libavcodec initialized (interface 3276801 )
ffmpeg debug: postprocessing disabled
ffmpeg debug: ffmpeg codec (h264) started
main debug: using decoder module "ffmpeg"
main debug: thread 3868 (decoder) created at priority 0
(src/input/decoder.c:159)
main debug: `E:\Shailesh\H264_DePack_OLD\Copy of H264_pkt_loss.264'
successfully opened
main debug: no usable vout present, spawning one
main debug: window size: 144x176
main debug: looking for video output module: 5 candidates
vout_directx debug: creating DirectXEventThread
main debug: waiting for thread completion
vout_directx debug: DirectXCreateWindow
vout_directx debug: Created video sub-window
main debug: thread 3888 (DirectX Events Thread) created at priority 0 (
directx.c:261)
vout_directx debug: DirectXEventThread running
vout_directx debug: DirectXInitDDraw
vout_directx debug: directx-device:
vout_directx debug: DirectXEnumCallback: Primary Display Driver, display
vout_directx debug: screen dimensions (0x0,1024x768)
vout_directx debug: DirectDraw Capabilities: overlay=1 yuvoverlay=1
can_deinterlace_overlay=1 colorkey=1 stretch=1 bltfourcc=1
vout_directx debug: End DirectXInitDDraw
vout_directx debug: DirectXCreateDisplay
main debug: Registering subpicture channel, ID: 2
main debug: Registering subpicture channel, ID: 3
main debug: Registering subpicture channel, ID: 4
main debug: Registering subpicture channel, ID: 5
vout_directx debug: DirectXCreateClipper
main debug: using video output module "vout_directx"
main debug: waiting for thread completion
vout_directx debug: NewPictureVec overlay:yes chroma:YV12
vout_directx debug: YUV overlay created successfully
vout_directx debug: End NewPictureVec (succeeded)
main debug: got 1 direct buffer(s)
main debug: picture in 144x176 (0,0,144x176), chroma I420, ar 58909:72000,
sar 1:1
main debug: picture user 144x176 (0,0,144x176), chroma I420, ar 58909:72000,
sar 1:1
main debug: picture out 144x176 (0,0,144x176), chroma I420, ar 58909:72000,
sar 1:1
main debug: direct render, mapping render pictures 0-6 to system pictures
1-7
main debug: thread 3916 (video output) created at priority 1
(src/video_output/video_output.c:416)
main warning: late picture skipped (171614)
main warning: late picture skipped (131639)
main warning: late picture skipped (91648)
main warning: late picture skipped (57075)
main warning: late picture skipped (17096)*

**

what do the highlighted warnings mean. What do the numbers enclosed in the
brackets

signify.

How does the player modify frame rate, Is there any error concealment
algorithm in place for packet loss since the quality of decoded output was
very good (no jerkiness or blockiness due to missing packets)



Regards

Neeraj
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