The backwards scanning done for incomplete final packets should not assume a specific alignment at the end of the file. Truncated files result in hundreds of thousands of seeks if the final packet does not fall on a specific byte boundary, which can be extremely slow. For example, with HTTP, each backwards seek results in a separate HTTP request. This changes the scanning to check for the end tag 1 byte at a time and buffers the last 1 MiB to avoid additional seek operations.
Unified · Split
| @@ -22,6 +22,7 @@ · 21 unmodified lines | |||
| 22 | 22 | ||
| 23 | #include <time.h> | 23 | #include <time.h> |
| 24 | 24 | ||
| 25 | #include "libavutil/intreadwrite.h" | ||
| 25 | #include "libavutil/mem.h" | 26 | #include "libavutil/mem.h" |
| 26 | #include "libavutil/parseutils.h" | 27 | #include "libavutil/parseutils.h" |
| 27 | #include "avio_internal.h" | 28 | #include "avio_internal.h" |
| @@ -232,37 +233,60 @@ static void get_timeinfo(unsigned date, struct tm *timeinfo) · 204 unmodified lines | |||
| 232 | timeinfo->tm_sec = sec; | 233 | timeinfo->tm_sec = sec; |
| 233 | } | 234 | } |
| 234 | 235 | ||
| 236 | #define MAX_DURATION_BUFFER_SIZE (1024*1024) | ||
| 237 | |||
| 235 | static int64_t get_duration(AVFormatContext *s) | 238 | static int64_t get_duration(AVFormatContext *s) |
| 236 | { | 239 | { |
| 237 | DHAVContext *dhav = s->priv_data; | ||
| 238 | int64_t start_pos = avio_tell(s->pb); | 240 | int64_t start_pos = avio_tell(s->pb); |
| 241 | int64_t end_pos = -1; | ||
| 239 | int64_t start = 0, end = 0; | 242 | int64_t start = 0, end = 0; |
| 240 | struct tm timeinfo; | 243 | struct tm timeinfo; |
| 241 | int max_interations = 100000; | 244 | uint8_t *end_buffer; |
| 245 | int64_t end_buffer_size; | ||
| 246 | int64_t end_buffer_pos; | ||
| 247 | int64_t offset; | ||
| 248 | unsigned date; | ||
| 242 | 249 | ||
| 243 | if (!s->pb->seekable) | 250 | if (!s->pb->seekable) |
| 244 | return 0; | 251 | return 0; |
| 245 | 252 | ||
| 246 | avio_seek(s->pb, avio_size(s->pb) - 8, SEEK_SET); | 253 | if (start_pos + 16 > avio_size(s->pb)) |
| 247 | while (avio_tell(s->pb) > 12 && max_interations--) { | 254 | return 0; |
| 248 | if (avio_rl32(s->pb) == MKTAG('d','h','a','v')) { | ||
| 249 | int64_t seek_back = avio_rl32(s->pb); | ||
| 250 | 255 | ||
| 251 | avio_seek(s->pb, -seek_back, SEEK_CUR); | 256 | avio_skip(s->pb, 16); |
| 252 | read_chunk(s); | 257 | date = avio_rl32(s->pb); |
| 253 | get_timeinfo(dhav->date, &timeinfo); | 258 | get_timeinfo(date, &timeinfo); |
| 254 | end = av_timegm(&timeinfo) * 1000LL; | 259 | start = av_timegm(&timeinfo) * 1000LL; |
| 260 | |||
| 261 | end_buffer_size = FFMIN(MAX_DURATION_BUFFER_SIZE, avio_size(s->pb)); | ||
| 262 | end_buffer = av_malloc(end_buffer_size); | ||
| 263 | if (!end_buffer) { | ||
| 264 | avio_seek(s->pb, start_pos, SEEK_SET); | ||
| 265 | return 0; | ||
| 266 | } | ||
| 267 | end_buffer_pos = avio_size(s->pb) - end_buffer_size; | ||
| 268 | avio_seek(s->pb, end_buffer_pos, SEEK_SET); | ||
| 269 | avio_read(s->pb, end_buffer, end_buffer_size); | ||
| 270 | |||
| 271 | offset = end_buffer_size - 8; | ||
| 272 | while (offset > 0) { | ||
| 273 | if (AV_RL32(end_buffer + offset) == MKTAG('d','h','a','v')) { | ||
| 274 | int64_t seek_back = AV_RL32(end_buffer + offset + 4); | ||
| 275 | end_pos = end_buffer_pos + offset - seek_back + 8; | ||
| 255 | break; | 276 | break; |
| 256 | } else { | 277 | } else { |
| 257 | avio_seek(s->pb, -12, SEEK_CUR); | 278 | offset -= 9; |
| 258 | } | 279 | } |
| 259 | } | 280 | } |
| 260 | 281 | ||
| 261 | avio_seek(s->pb, start_pos, SEEK_SET); | 282 | if (end_pos < 0 || end_pos + 16 > end_buffer_pos + end_buffer_size) { |
| 283 | avio_seek(s->pb, start_pos, SEEK_SET); | ||
| 284 | return 0; | ||
| 285 | } | ||
| 262 | 286 | ||
| 263 | read_chunk(s); | 287 | date = AV_RL32(end_buffer + (end_pos - end_buffer_pos) + 16); |
| 264 | get_timeinfo(dhav->date, &timeinfo); | 288 | get_timeinfo(date, &timeinfo); |
| 265 | start = av_timegm(&timeinfo) * 1000LL; | 289 | end = av_timegm(&timeinfo) * 1000LL; |
| 266 | 290 | ||
| 267 | avio_seek(s->pb, start_pos, SEEK_SET); | 291 | avio_seek(s->pb, start_pos, SEEK_SET); |
| 268 | 292 | ||