From: Andriy Gelman <andriy.gel...@gmail.com>
Reduces buffering during estimation of mpegts raw_packet_size
parameter. Instead of buffering a fixed 8192 bytes, calculate
probe scores on a smaller buffer. Increase buffer size until
probe score is greater than minimum value.
---
libavformat/mpegts.c | 82 +++++++++++++++++++++++++++++++-------------
1 file changed, 59 insertions(+), 23 deletions(-)
diff --git a/libavformat/mpegts.c b/libavformat/mpegts.c
index b04fd7b4f4..a7b33eae69 100644
--- a/libavformat/mpegts.c
+++ b/libavformat/mpegts.c
@@ -53,6 +53,10 @@
(prev_dividend) = (dividend);
\
} while (0)
+#define MAX_RAW_PACKET_PROBE 8192
+#define PROBE_PACKET_STEP 512
+#define RAW_PACKET_MIN_SCORE 10
+
enum MpegTSFilterType {
MPEGTS_PES,
MPEGTS_SECTION,
@@ -591,28 +595,64 @@ static int analyze(const uint8_t *buf, int size, int
packet_size,
return best_score - FFMAX(stat_all - 10*best_score, 0)/10;
}
-/* autodetect fec presence. Must have at least 1024 bytes */
-static int get_packet_size(const uint8_t *buf, int size)
+/* autodetect fec presence */
+static int get_packet_size(AVIOContext* pb)
{
int score, fec_score, dvhs_score;
+ int pd_packet_size = TS_PACKET_SIZE;
+ int best_score = 0;
+ int ret;
- if (size < (TS_FEC_PACKET_SIZE * 5 + 1))
- return AVERROR_INVALIDDATA;
+ AVProbeData pd = { 0 };
+ while (best_score < RAW_PACKET_MIN_SCORE &&
+ pd.buf_size + PROBE_PACKET_STEP <= MAX_RAW_PACKET_PROBE) {
+
+ /*create extra space for next packet*/
+ uint8_t *new_buf = av_realloc(pd.buf, pd.buf_size + PROBE_PACKET_STEP);
+ if (new_buf) {
+ pd.buf = new_buf;
+ ret = avio_read(pb, pd.buf + pd.buf_size, PROBE_PACKET_STEP);
+ if (ret < 0) {
+ av_log(pb, AV_LOG_ERROR, "Error reading from input: %s.\n",
+ av_err2str(ret));
+ break;
+ }
+ pd.buf_size += ret;
+ } else
+ goto fail;
+
+ /*check score for each fec packet size*/
+ score = analyze(pd.buf, pd.buf_size, TS_PACKET_SIZE, 0);
+ if (score > best_score) {
+ best_score = score;
+ pd_packet_size = TS_PACKET_SIZE;
+ }
- score = analyze(buf, size, TS_PACKET_SIZE, 0);
- dvhs_score = analyze(buf, size, TS_DVHS_PACKET_SIZE, 0);
- fec_score = analyze(buf, size, TS_FEC_PACKET_SIZE, 0);
- av_log(NULL, AV_LOG_TRACE, "score: %d, dvhs_score: %d, fec_score: %d \n",
- score, dvhs_score, fec_score);
-
- if (score > fec_score && score > dvhs_score)
- return TS_PACKET_SIZE;
- else if (dvhs_score > score && dvhs_score > fec_score)
- return TS_DVHS_PACKET_SIZE;
- else if (score < fec_score && dvhs_score < fec_score)
- return TS_FEC_PACKET_SIZE;
- else
- return AVERROR_INVALIDDATA;
+ dvhs_score = analyze(pd.buf, pd.buf_size, TS_DVHS_PACKET_SIZE, 0);
+ if (dvhs_score > best_score) {
+ best_score = dvhs_score;
+ pd_packet_size = TS_DVHS_PACKET_SIZE;
+ }
+
+ fec_score = analyze(pd.buf, pd.buf_size, TS_FEC_PACKET_SIZE, 0);
+ if (fec_score > best_score) {
+ best_score = fec_score;
+ pd_packet_size = TS_FEC_PACKET_SIZE;
+ }
+
+ av_log(NULL, AV_LOG_TRACE, "Probe size: %d, score: %d, dvhs_score: %d,
fec_score: %d \n",
+ pd.buf_size, score, dvhs_score, fec_score);
+ }
+
+ if (pd.buf)
+ av_freep(&pd.buf);
+
+ return pd_packet_size;
+
+fail:
+ if (pd.buf)
+ av_freep(&pd.buf);
+ return AVERROR(ENOMEM);
}
typedef struct SectionHeader {
@@ -2841,8 +2881,6 @@ static int mpegts_read_header(AVFormatContext *s)
{
MpegTSContext *ts = s->priv_data;
AVIOContext *pb = s->pb;
- uint8_t buf[8 * 1024] = {0};
- int len;
int64_t pos, probesize = s->probesize;
s->internal->prefer_codec_framerate = 1;
@@ -2850,10 +2888,8 @@ static int mpegts_read_header(AVFormatContext *s)
if (ffio_ensure_seekback(pb, probesize) < 0)
av_log(s, AV_LOG_WARNING, "Failed to allocate buffers for seekback\n");
- /* read the first 8192 bytes to get packet size */
pos = avio_tell(pb);
- len = avio_read(pb, buf, sizeof(buf));
- ts->raw_packet_size = get_packet_size(buf, len);
+ ts->raw_packet_size = get_packet_size(pb);
if (ts->raw_packet_size <= 0) {
av_log(s, AV_LOG_WARNING, "Could not detect TS packet size, defaulting
to non-FEC/DVHS\n");
ts->raw_packet_size = TS_PACKET_SIZE;
--
2.20.1
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