[FFmpeg-devel] [PATCH 0/7] using ffmpeg as an RTSP client

[Gilles Chanteperdrix]

Hi,

I am using ffmpeg 2.5.3 as an RTSP client and found a few missing
pieces, which the following series of patches should address. I used
some test files streamed with an RTSP server on the xenomai.org
server, the files are available for download by replacing
rtsp://xenomai.org:8554 with https://xenomai.org in the URL

- support for depacketization of AC3 RTP frames is missing, patch 1
adds it, following https://tools.ietf.org/html/draft-ietf-avt-rtp-ac3-07
it can be tested with:
rtsp://xenomai.org:8554/video-tests/big_buck_bunny/BigBuckBunny_DivX_HD720p_ASP.divx
(using audio track 2, as audio track 1 uses mp3adu)

- support for receiving sub-titles via RTP is missing. live555 uses
the T140 RTP packetization for that (RFC 4103), and vlc decodes
subrip subtitles sent that way. Patch 2 and 3 implement a compatible
solution, meaning that the AV_CODEC_ID_SUBRIP is used for T140
tracks, of course another codec id could be used. These patches can
be tested with:
rtsp://xenomai.org:8554/video-tests/sintel/sintel-1280-surround.mp4

- support for receiving MP3ADU audio via RTP, following RFC 3119 is
missing. Patch 4 modifies the MPEG audio parser to decode MP3ADU
headers in MP3ADU frames only when the PARSER_FLAG_COMPLETE_FRAMES
is set, because for some reason the parser creates incorrect frames
when trying to parse MP3ADU frames fully with the test file I used.
Patch 5 implements the depacketizer. These patches can be tested
with:
rtsp://xenomai.org:8554/video-tests/big_buck_bunny/BigBuckBunny_DivX_HD720p_ASP.divx
(this time using audio track 1)

- support for reassembly of fragmented AAC frames via RTP is
missing. Patch 6 modifies libavformat/rtpdec_mpeg4.c to add that
support. This patch can be tested with:
rtsp://xenomai.org:8554/video-tests/sintel/sintel-1280-surround.mp4
Without this patch, fragmented AAC frames are silently dropped,
which causes underruns in the audio driver when playing the test
file.

- support for parsing the lang attribute in RTSP tracks is missing.
Patch 7 adds it. This patch can be tested with:
rtsp://xenomai.org:8554/video-tests/sintel/sintel-1280-surround.mp4
Launching ffprobe with this URL should display the languages of the
audio track and subtitle tracks.

Thanks in advance for your review.
Regards.

-- 
					    Gilles.