Fix for distortions at file split points [was: Re: [ANNOUNCE] VDR developer version 1.7.19]
Commit Message
On 20.06.2011 00:22, Udo Richter wrote:
> Am 19.06.2011 22:57, schrieb Klaus Schmidinger:
>> On 19.06.2011 12:41, Klaus Schmidinger wrote:
>>> - Fixed detecting frames in case the Picture Start Code or Access Unit
>>> Delimiter
>>> extends over TS packet boundaries (reported by Johan Andersson).
>>
>> I'm afraid this change causes a short distortion in video and audio
>> when VDR switches from one .ts file to the next during replay.
>> I have yet to investigate and fix this, just wanted to warn people
>> who make important recordings with this new version - which, of course,
>> nobody should do, since it is a developer version ;-)
>
> Thanks for the hint, reverted to 1.7.18 for now. Or, of course, would
> have if I were using a developer version, which nobody would do. ;)
>
> Can you provide a diff that reverts just that changeset so we can use
> all the other goodies of 1.7.19 for now? Eh, could, if we would use
> developer builds, of course. ;)
Please try the attached patch with VDR 1.7.19.
cRecorder::Action() now buffers TS packets in case the frame type is
not yet known when a new payload starts. This adds no overhead for channels
that broadcast the frame type within the first TS packet of a payload; it only
kicks in if that information is not in the first TS packet.
For testing you may want to set MaxVideoFileSize (in setup.conf) to
a lower value, so that recordings are split into many files.
Since I don't know of any channel I can receive that doesn't encode
the picture type in the first TS packet of a new payload, I was only
able to test whether the distortion problem is gone for "normal"
channels ("unnormal" being those that don't encode the picture type
in the first TS packet ;-). Therefore the actual buffering functionality
is untested.
If you get a "frame type not in first packet of payload - buffering"
or any other of the new log messages, please let me know.
Klaus
@@ -10,7 +10,7 @@
#include "recorder.h"
#include "shutdown.h"
-#define RECORDERBUFSIZE MEGABYTE(5)
+#define RECORDERBUFSIZE (MEGABYTE(5) / TS_SIZE * TS_SIZE) // multiple of TS_SIZE
// The maximum time we wait before assuming that a recorded video data stream
// is broken:
@@ -88,7 +88,7 @@
bool cRecorder::NextFile(void)
{
- if (recordFile && frameDetector->IndependentFrame()) { // every file shall start with an independent frame
+ if (recordFile) {
if (fileSize > MEGABYTE(off_t(Setup.MaxVideoFileSize)) || RunningLowOnDiskSpace()) {
recordFile = fileName->NextFile();
fileSize = 0;
@@ -119,8 +119,11 @@
time_t t = time(NULL);
bool InfoWritten = false;
bool FirstIframeSeen = false;
- int FileNumber = 0;
- off_t FrameOffset = -1;
+#define BUFFERSIZE MEGABYTE(1)
+ bool Buffering = false;
+ int BufferIndex = 0;
+ int MaxBufferIndex = 0;
+ uchar *Buffer = NULL;
while (Running()) {
int r;
uchar *b = ringBuffer->Get(r);
@@ -141,16 +144,37 @@
}
InfoWritten = true;
}
- if (frameDetector->NewPayload()) {
- FileNumber = fileName->Number();
- FrameOffset = fileSize;
+ if (frameDetector->NewPayload()) { // We're at the first TS packet of a new payload...
+ if (Buffering)
+ esyslog("ERROR: encountered new payload while buffering - dropping some data!");
+ if (!frameDetector->NewFrame()) { // ...but the frame type is yet unknown, so we need to buffer packets until we see the frame type
+ if (!Buffer) {
+ dsyslog("frame type not in first packet of payload - buffering");
+ if (!(Buffer = MALLOC(uchar, BUFFERSIZE))) {
+ esyslog("ERROR: can't allocate frame type buffer");
+ break;
+ }
+ }
+ BufferIndex = 0;
+ Buffering = true;
+ }
}
- if (FirstIframeSeen || frameDetector->IndependentFrame()) {
+ else if (frameDetector->NewFrame()) // now we know the frame type, so stop buffering
+ Buffering = false;
+ if (Buffering) {
+ if (BufferIndex + Count <= BUFFERSIZE) {
+ memcpy(Buffer + BufferIndex, b, Count);
+ BufferIndex += Count;
+ }
+ else
+ esyslog("ERROR: too many bytes for frame type buffer (%d > %d) - dropped %d bytes", BufferIndex + Count, int(BUFFERSIZE), Count);
+ }
+ else if (FirstIframeSeen || frameDetector->IndependentFrame()) {
FirstIframeSeen = true; // start recording with the first I-frame
- if (!NextFile())
+ if (frameDetector->IndependentFrame() && !NextFile()) // every file shall start with an independent frame
break;
if (index && frameDetector->NewFrame())
- index->Write(frameDetector->IndependentFrame(), FileNumber, FrameOffset);
+ index->Write(frameDetector->IndependentFrame(), fileName->Number(), fileSize);
if (frameDetector->IndependentFrame()) {
recordFile->Write(patPmtGenerator.GetPat(), TS_SIZE);
fileSize += TS_SIZE;
@@ -160,6 +184,12 @@
fileSize += TS_SIZE;
}
}
+ if (BufferIndex) {
+ recordFile->Write(Buffer, BufferIndex); // if an error occurs here, the next write below will catch and report it
+ if (BufferIndex > MaxBufferIndex)
+ MaxBufferIndex = BufferIndex;
+ BufferIndex = 0;
+ }
if (recordFile->Write(b, Count) < 0) {
LOG_ERROR_STR(fileName->Name());
break;
@@ -177,4 +207,8 @@
t = time(NULL);
}
}
+ if (Buffer) {
+ free(Buffer);
+ dsyslog("frame type buffer used %d bytes", MaxBufferIndex);
+ }
}