[FFmpeg-devel] [PATCH] support for flvtool2 "keyframes based" generated index in FLV format decoder
Anton Khirnov
anton
Wed Feb 9 20:15:03 CET 2011
> Index: libavformat/flvdec.c
> ===================================================================
> --- libavformat/flvdec.c (revision 26402)
> +++ libavformat/flvdec.c (working copy)
> @@ -30,6 +30,10 @@
> #include "avformat.h"
> #include "flv.h"
>
> +#define METADATA_KEYFRAMES_TAG "keyframes"
> +#define METADATA_KEYFRAMES_TIMESTAMP_TAG "times"
> +#define METADATA_KEYFRAMES_BYTEOFFSET_TAG "filepositions"
> +
> typedef struct {
> int wrong_dts; ///< wrong dts due to negative cts
> } FLVContext;
> @@ -124,6 +128,63 @@
> return length;
> }
>
> +static int try_parse_keyframes_index(AVFormatContext *s, ByteIOContext *ioc, AVStream *vstream, int64_t max_pos) {
nit: the 'try_' part carries no information, get rid of it.
> + unsigned int keylen, arraylen = 0, timeslen = 0, fileposlen = 0, i;
> + double num_val;
> + AMFDataType amf_type;
> + char str_val[256];
> + int64_t *times = 0;
> + int64_t *filepositions = 0;
You mean NULL
> +
> + while (url_ftell(ioc) < max_pos - 2 && (keylen = get_be16(ioc))) {
> + int64_t* current_array;
> + // Read array name from context
> + get_buffer(ioc, str_val, keylen);
> + str_val[keylen] = '\0';
Buffer overflow.
> +
> + // Expect array object in context
> + amf_type = get_byte(ioc);
> + if (amf_type != AMF_DATA_TYPE_ARRAY)
This value isn't used anywhere else, so you can use if (get_byte() ...)
and get rid of amf_type. Same below.
> + return -1;
> +
> + arraylen = get_be32(ioc);
> + /*
> + * Expect only 'times' or 'filepositions' sub-arrays in other case refuse to use such metadata
> + * for indexing
> + */
> + if (!strcmp(METADATA_KEYFRAMES_TIMESTAMP_TAG, str_val)) {
> + times = av_mallocz(sizeof(int64_t) * arraylen);
Use sizeof(*times). Also you should check that malloc succeeded (it
might easily fail with a corrupted file).
> + timeslen = arraylen;
> + current_array = times;
> + } else if (!strcmp(METADATA_KEYFRAMES_BYTEOFFSET_TAG, str_val)) {
> + filepositions = av_mallocz(sizeof(int64_t) * arraylen);
> + fileposlen = arraylen;
> + current_array = filepositions;
> + } else
> + // unexpected metatag inside keyframes, will not use such metadata for indexing
> + return -1;
> +
> + for(i = 0; i < arraylen && url_ftell(ioc) < max_pos - 1; i++) {
> + amf_type = get_byte(ioc);
> + if (amf_type != AMF_DATA_TYPE_NUMBER)
> + return -1;
Memleak. Same below.
> + num_val = av_int2dbl(get_be64(ioc));
> + current_array[i] = num_val;
> + }
> + }
> + if(timeslen != fileposlen)
> + // times->filepositions arrays have different size, will not use such metadata for indexing
> + return -1;
> +
> + for(i = 0; i < arraylen; ++i) {
> + av_add_index_entry(vstream, filepositions[i], times[i]*1000, 0, 0, AVINDEX_KEYFRAME);
> + }
> +
> + av_freep(×);
> + av_freep(&filepositions);
> + return 0;
> +}
> +
> static int amf_parse_object(AVFormatContext *s, AVStream *astream, AVStream *vstream, const char *key, int64_t max_pos, int depth) {
> AVCodecContext *acodec, *vcodec;
> ByteIOContext *ioc;
> @@ -148,6 +209,17 @@
> case AMF_DATA_TYPE_OBJECT: {
> unsigned int keylen;
>
> + if (!strcmp(METADATA_KEYFRAMES_TAG, key) && depth == 1) {
> + int64_t cur_ioc_pos = url_ftell(ioc);
> + /*
> + * Try parse keyframes metatag and fill AV index.
> + * Reset stream to initial state after that to run default parser
> + * to not break default parser behavior
> + */
> + if(try_parse_keyframes_index(s, ioc, vstream, max_pos) < 0)
> + url_fseek(ioc, cur_ioc_pos, SEEK_SET);
> + }
> +
> while(url_ftell(ioc) < max_pos - 2 && (keylen = get_be16(ioc))) {
> url_fskip(ioc, keylen); //skip key string
> if(amf_parse_object(s, NULL, NULL, NULL, max_pos, depth + 1) < 0)
--
Anton Khirnov
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