Good news. A fix for this was posted to the mplayer list today. I have
compiled a Windows version and have been using it today without any
problems. We will have to wait for an official mplayer release but if
you want to compile it yourself here is the change.
Bryan Alton Wrote:
> I think have a fix for this problem. I have tested it with all the BBC
> live real streams and it seems to work. I haven't tested to see if it
> interferes with other Real streams. A few times Mplayer has stopped, I
> don't know if this is as a result of my fix or just the network. My
> tests were run on SuSe 9.3 and I will be building a Windows version as
> soon as I setup a compile environment.
>
> The messages in the fix will be gewnerated with -v 1 so that you can
> see if packet loss was detected. I fill in the gaps with the previous
> packet which result in a short burst of choppy audio. If you get a
> burst of errors, then you will hear a longer burst of choppy audio but
> the stream usually settles down. I can live with this but I can
> suggest a better solution if somebody wants to do the work.
>
> My changes are to one file libmpdemux/demux_real.c. A diff file is
> included below. I made the changed to a recent release but
> demux_real.c hasn't changed much in months so the changes will work
> back to other versions.
>
> The cut & paste may have messed some lines but I hope you use it.
>
>
> >
Code:
--------------------
> >
> *** demux_real.c 2005-09-26 15:53:26.000000000 +0100
> --- demux_real.c.orig 2005-09-25 23:47:44.000000000 +0100
> *************** typedef struct {
> *** 92,105 ****
> int a_bitrate; ///< Audio bitrate
> int v_bitrate; ///< Video bitrate
> int stream_switch; ///< Flag used to switch audio/video demuxing
> -
> - /* Variables to fix missing buffer in stream audio */
> - int live_stream; // Flag to indicate that it is a live
audio only stream
> - int ms_per_packet; // millisec per pack - used to detect if
a packet is missed
> - int ms_per_block; // millsec per block (usually made up 16
packets)
> - int ms_per_packet_safety; // Since timing is not precise - a safety
margin is needed - guess about 20% of packet time.
> -
> -
> } real_priv_t;
>
> /* originally from FFmpeg */
> --- 92,97 ----
> *************** got_audio:
> *** 695,721 ****
> priv->audio_need_keyframe = 0;
> }else
> dp->pts = (priv->a_pts==timestamp) ? 0 : (timestamp/1000.0f);
> - /*************************/
> -
> - if ( (priv->live_stream == 1) &&
(((sh_audio_t*)ds->sh)->format == mmioFOURCC('c','o','o','k')) ){ // Not sure
if missingpacket happen the same way for other formats
> -
> - demux_packet_t *dp1;
> - if (((timestamp - priv->a_pts) >
priv->ms_per_packet_safety)&& ((timestamp - priv->a_pts) < priv->ms_per_block))
> - mp_msg(MSGT_DEMUX,MSGL_V, "Packet timestamp gap
Actual %7d msec Expected %7d Flags %02X\n",
timestamp-priv->a_pts,priv->ms_per_packet,dp->flags);
> - if (((timestamp - priv->a_pts) < priv->ms_per_packet))
> - mp_msg(MSGT_DEMUX,MSGL_V, "Packet timestamp gap too
short Actual %7d msec Expected %7d Flags %02X\n",
timestamp-priv->a_pts,priv->ms_per_packet,dp->flags);
> -
> - while( ((timestamp - priv->a_pts) >
priv->ms_per_packet_safety) && (timestamp - priv->a_pts) < priv->ms_per_block) {
> - dp1 = new_demux_packet(len);
> - memcpy(dp1->buffer,dp->buffer,len);
> - priv->a_pts=priv->a_pts + priv->ms_per_packet;
> - dp1->pos = demuxer->filepos;
> - dp1->flags = 0;
> - ds_add_packet(ds, dp1);
> - }
> - }
> - /**************************/
> -
> priv->a_pts=timestamp;
> dp->pos = demuxer->filepos;
> dp->flags = (flags & 0x2) ? 0x10 : 0;
> --- 687,692 ----
> *************** static demuxer_t* demux_open_real(demuxe
> *** 1158,1169 ****
>
> if (!strncmp(mimet,"audio/",6)) {
> if (strstr(mimet,"x-pn-realaudio") ||
strstr(mimet,"x-pn-multirate-realaudio")) {
> -
> - if (strstr(mimet,"x-pn-multirate-realaudio-live" )) {
> - priv->live_stream = 1;
> - } else
> - priv->live_stream = 0;
> -
> // skip unknown shit - FIXME: find a better/cleaner way!
> len=codec_data_size;
> tmp = stream_read_dword(demuxer->stream);
> --- 1130,1135 ----
> *************** static demuxer_t* demux_open_real(demuxe
> *** 1392,1406 ****
> ((short*)(sh->wf+1))[4]=codecdata_length;
> // stream_read(demuxer->stream,
((char*)(sh->wf+1))+6, 24); // extras
> stream_read(demuxer->stream, ((char*)(sh->wf+1))+10, codecdata_length); //
extras
> - priv->ms_per_packet = (long)
((coded_frame_size*8*1000L)/(sh->wf->nAvgBytesPerSec)); // I think variable
should be avgbits/sec
> - priv->ms_per_packet_safety =
priv->ms_per_packet + (priv->ms_per_packet/5) ; // Add 20% for the safety margin
> - priv->ms_per_block = priv->ms_per_packet *
sub_packet_h;
> - priv->ms_per_packet--; // Empircally - round
down to suit observed actual gaps
> - if (priv->live_stream == 1){
> - mp_msg(MSGT_DEMUX,MSGL_V,"Live stream:
Subpacksize %d sub packet h %d Flavour %d coded frame size %d codecdatalength
%d avg byte/sec %d channels
%d\n",sub_packet_size,sub_packet_h,flavor,coded_frame_size,codecdata_length,
sh->wf->nAvgBytesPerSec, sh->channels);
> - mp_msg(MSGT_DEMUX,MSGL_V,"Live stream:
Expected range ms/packet %d to %d ms per block
%d\n",priv->ms_per_packet,priv->ms_per_packet_safety, priv->ms_per_block);
> - }
> -
> break;
> case MKTAG('r', 'a', 'a', 'c'):
> case MKTAG('r', 'a', 'c', 'p'):
> --- 1358,1363 ----
>
--------------------
> >
>
--
Neil Sleightholm
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