[FFmpeg-devel] [PATCH v3] avformat/rtpdec_rfc4175: support non-zero based line numbers
Michael Niedermayer
michael at niedermayer.cc
Thu Nov 7 23:35:25 EET 2019
On Thu, Nov 07, 2019 at 10:27:31PM +0800, Kah Goh wrote:
> On Mon, Sep 30, 2019 at 09:27:20PM +0800, Kah Goh wrote:
> > There are differing standards that define different starting line
> > numbers. For example, VSF TR-03 says the line numbers starts at 1,
> > whereas SMPTE 2110-20 says it should start at 0.
> >
> > This change adds support for non-zero based line numbers and addresses
> > the following issues when it starts at 1:
> > - The first scan line was being incorrectly interpreted as the second
> > scan line. This means the first line in the frame was never being
> > populated.
> > - The last packet for the video frame would be treated as invalid
> > because it would have been copied outside of the frame. Consequently,
> > the packet would never be "finalized" and the next packet triggers a
> > missed RTP marker ("Missed previous RTP marker" would keep being
> > logged).
> >
> > VSF TR-03: http://www.videoservicesforum.org/download/technical_recommendations/VSF_TR-03_2015-11-12.pdf
> >
> > Co-Authored-By: Jacob Siddall <kobe at live.com.au>
> > Co-Authored-By: Kah Goh <villastar at yahoo.com.au>
> > Signed-off-by: Kah Goh <villastar at yahoo.com.au>
> > ---
> > libavformat/rtpdec_rfc4175.c | 49 +++++++++++++++++++++++++++++++++---
> > 1 file changed, 45 insertions(+), 4 deletions(-)
> >
> > diff --git a/libavformat/rtpdec_rfc4175.c b/libavformat/rtpdec_rfc4175.c
> > index e9c62c1389..47d5d23dd6 100644
> > --- a/libavformat/rtpdec_rfc4175.c
> > +++ b/libavformat/rtpdec_rfc4175.c
> > @@ -25,6 +25,7 @@
> > #include "rtpdec_formats.h"
> > #include "libavutil/avstring.h"
> > #include "libavutil/pixdesc.h"
> > +#include <stdbool.h>
> >
> > struct PayloadContext {
> > char *sampling;
> > @@ -37,6 +38,12 @@ struct PayloadContext {
> > unsigned int pgroup; /* size of the pixel group in bytes */
> > unsigned int xinc;
> >
> > + /* The line number of the first line in the frame (usually either 0 or 1). */
> > + int first_line_number;
> > +
> > + /* This is set to true once the first line number is confirmed. */
> > + bool first_line_number_known;
> > +
> > uint32_t timestamp;
> > };
> >
> > @@ -136,6 +143,13 @@ static int rfc4175_finalize_packet(PayloadContext *data, AVPacket *pkt,
> > return ret;
> > }
> >
> > +static int rfc4175_initialize(AVFormatContext *s, int st_index, PayloadContext *data)
> > +{
> > + data->first_line_number = 0;
> > + data->first_line_number_known = false;
> > + return 0;
> > +}
> > +
> > static int rfc4175_handle_packet(AVFormatContext *ctx, PayloadContext *data,
> > AVStream *st, AVPacket *pkt, uint32_t *timestamp,
> > const uint8_t * buf, int len,
> > @@ -188,7 +202,7 @@ static int rfc4175_handle_packet(AVFormatContext *ctx, PayloadContext *data,
> >
> > /* and now iterate over every scan lines */
> > do {
> > - int copy_offset;
> > + int copy_offset, copy_to_line;
> >
> > if (payload_len < data->pgroup)
> > return AVERROR_INVALIDDATA;
> > @@ -199,17 +213,34 @@ static int rfc4175_handle_packet(AVFormatContext *ctx, PayloadContext *data,
> > cont = headers[4] & 0x80;
> > headers += 6;
> >
> > + if (line == 0) {
> > + data->first_line_number = 0;
> > + data->first_line_number_known = true;
> > + }
> > +
> > if (length % data->pgroup)
> > return AVERROR_INVALIDDATA;
> >
> > if (length > payload_len)
> > length = payload_len;
> >
> > - /* prevent ill-formed packets to write after buffer's end */
> > - copy_offset = (line * data->width + offset) * data->pgroup / data->xinc;
> > - if (copy_offset + length > data->frame_size)
> > + copy_to_line = line - data->first_line_number;
> > + if (copy_to_line < 0)
> > + /* This means the first line number we have calculated is too large, which indicates that we
> > + may have received some bad data. */
> > return AVERROR_INVALIDDATA;
> >
> > + /* prevent ill-formed packets to write after buffer's end */
> > + copy_offset = (copy_to_line * data->width + offset) * data->pgroup / data->xinc;
> > + if (copy_offset + length > data->frame_size) {
> > + if (data->first_line_number_known)
> > + return AVERROR_INVALIDDATA;
> > +
> > + // This would happen if the line numbering is 1 based. We still need to check for the RTP flag
> > + // marker (as per after the while loop).
> > + break;
> > + }
> > +
> > dest = data->frame + copy_offset;
> > memcpy(dest, payload, length);
> >
> > @@ -218,6 +249,15 @@ static int rfc4175_handle_packet(AVFormatContext *ctx, PayloadContext *data,
> > } while (cont);
> >
> > if ((flags & RTP_FLAG_MARKER)) {
> > + if (!data->first_line_number_known) {
> > + data->first_line_number = line - data->height + 1;
> > + if (data->first_line_number < 0) {
> > + // This could happen if the frame does not fill up the entire height.
> > + data->first_line_number = 0;
> > + av_log(ctx, AV_LOG_WARNING, "Video frame does not fill entire height");
> > + }
> > + data->first_line_number_known = true;
> > + }
> > return rfc4175_finalize_packet(data, pkt, st->index);
> > } else if (missed_last_packet) {
> > return 0;
> > @@ -232,5 +272,6 @@ const RTPDynamicProtocolHandler ff_rfc4175_rtp_handler = {
> > .codec_id = AV_CODEC_ID_BITPACKED,
> > .priv_data_size = sizeof(PayloadContext),
> > .parse_sdp_a_line = rfc4175_parse_sdp_line,
> > + .init = rfc4175_initialize,
> > .parse_packet = rfc4175_handle_packet,
> > };
> > --
> > 2.23.0
> >
>
> Ping
I see there are multiple People working on this and others who worked
previously on this. Can one of the people working on this code
please review this ?
Iam happy to apply it if its reviewed (assuming noone spots anything
bad of course)
Thanks
[...]
--
Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
He who knows, does not speak. He who speaks, does not know. -- Lao Tsu
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